Chapter 37
UTRICULARIA (continued).
Utricularia montana—Description of the bladders on the subterranean rhizomes—Prey captured by the bladders of plants under culture and in a state of nature—Absorption by the quadrifid processes and glands—Tubers serving as reservoirs for water—Various other species of Utricularia—Polypompholyx—Genlisea, different nature of the trap for capturing prey— Diversified methods by which plants are nourished.
FIG. 26. (Utricularia montana.) Rhizome swollen into a tuber; the branches bearing minute bladders; of natural size.
Utricularia montana.—This species inhabits the tropical parts of South America, and is said to be epiphytic; but, judging from the state of the roots (rhizomes) of some dried specimens from the herbarium at Kew, it likewise lives in earth, probably in crevices of rocks. In English hothouses it is grown in peaty soil. Lady Dorothy Nevill was so kind as to give me a fine plant, and I received another from Dr. Hooker. The leaves are entire, instead of being much divided, as in the foregoing aquatic species. They are elongated, about 1 1/2 inch in breadth, and furnished with a distinct footstalk. The plant produces numerous colourless rhizomes, as thin as threads, which bear minute bladders, and occasionally swell into tubers, as will [page 432] hereafter be described. These rhizomes appear exactly like roots, but occasionally throw up green shoots. They penetrate the earth sometimes to the depth of more than 2 inches; but when the plant grows as an epiphyte, they must creep amidst the mosses, roots, decayed bark, &c., with which the trees of these countries are thickly covered.
As the bladders are attached to the rhizomes, they are necessarily subterranean. They are produced in extraordinary numbers. One of my plants, though young, must have borne several hundreds; for a single branch out of an entangled mass had thirty-two, and another branch, about 2 inches in length (but with its end and one side branch broken off), had seventy- three bladders.* The bladders are compressed and rounded, with the ventral surface, or that between the summit of the long delicate footstalk and valve, extremely short (fig. 27). They are colourless and almost as transparent as glass, so that they appear smaller than they really are, the largest being under the 1/20 of an inch (1.27 mm.) in its longer diameter. They are formed of rather large angular cells, at the junctions of which oblong papillae project, corresponding with those on the surfaces of the bladders of the previous species. Similar papillae abound on the rhizomes, and even on the entire leaves, but they are rather broader on the latter. Vessels, marked with parallel bars instead of by a spiral line, run up the footstalks, and
* Prof. Oliver has figured a plant of Utricularia Jamesoniana (‘Proc. Linn. Soc.’ vol. iv. p. 169) having entire leaves and rhizomes, like those of our present species; but the margins of the terminal halves of some of the leaves are converted into bladders. This fact clearly indicates that the bladders on the rhizomes of the present and following species are modified segments of the leaf; and they are thus brought into accordance with the bladders attached to the divided and floating leaves of the aquatic species. [page 433]
just enter the bases of the bladders; but they do not bifurcate and extend up the dorsal and ventral surfaces, as in the previous species.
The antennæ are of moderate length, and taper to a fine point; they differ conspicuously from those before described, in not being armed with bristles. Their bases are so abruptly curved that their tips generally rest one on each side of the middle of the bladder, but
FIG. 27. (Utricularia montana.) Bladder; about 27 times enlarged.
sometimes near the margin. Their curved bases thus form a roof over the cavity in which the valve lies; but there is always left on each side a little circular passage into the cavity, as may be seen in the drawing, as well as a narrow passage between the bases of the two antennæ. As the bladders are subterranean, had it not been for the roof, the cavity in which the valve lies would have been liable to be blocked up with earth [page 434] and rubbish; so that the curvature of the antennæ is a serviceable character. There are no bristles on the outside of the collar or peristome, as in the foregoing species.
The valve is small and steeply inclined, with its free posterior edge abutting against a semicircular, deeply depending collar. It is moderately transparent, and bears two pairs of short stiff bristles, in the same position as in the other species. The presence of these four bristles, in contrast with the absence of those on the antennæ and collar, indicates that they are of functional importance, namely, as I believe, to prevent too large animals forcing an entrance through the valve. The many glands of diverse shapes attached to the valve and round the collar in the previous species are here absent, with the exception of about a dozen of the two-armed or transversely elongated kind, which are seated near the borders of the valve, and are mounted on very short footstalks. These glands are only the 3/4000 of an inch (.019 mm.) in length; though so small, they act as absorbents. The collar is thick, stiff, and almost semi-circular; it is formed of the same peculiar brownish tissue as in the former species.
The bladders are filled with water, and sometimes include bubbles of air. They bear internally rather short, thick, quadrifid processes arranged in approximately concentric rows. The two pairs of arms of which they are formed differ only a little in length, and stand in a peculiar position (fig. 28); the two longer ones forming one line, and the two shorter ones another parallel line. Each arm includes a small spherical mass of brownish matter, which, when crushed, breaks into angular pieces. I have no doubt that these spheres are nuclei, for closely similar ones [page 435] are present in the cells forming the walls of the bladders. Bifid processes, having rather short oval arms, arise in the usual position on the inner side of the collar.
These bladders, therefore, resemble in all essential respects the larger ones of the foregoing species. They differ chiefly in the absence of the numerous glands on the valve and round the collar, a few minute ones of one kind alone being present on the valve. They differ more conspicuously in the absence of the long bristles on the antennæ and on the outside of the collar. The presence of these bristles in the previously mentioned species probably relates to the capture of aquatic animals.
FIG. 28. (Utricularia montana.) One of the quadrifid processes; much enlarged.
It seemed to me an interesting question whether the minute bladders of Utricularia montanaserved, as in the previous species, to capture animals living in the earth, or in the dense vegetation covering the trees on which this species is epiphytic; for in this case we should have a new sub-class of carnivorous plants, namely, subterranean feeders. Many bladders, therefore, were examined, with the following results:—
[(1) A small bladder, less than 1/30 of an inch (.847 mm.) in diameter, contained a minute mass of brown, much decayed matter; and in this, a tarsus with four or five joints, terminating in a double hook, was clearly distinguished under the microscope. I suspect that it was a remnant of one of the Thysanoura. The quadrifids in contact with this decayed remnant contained either small masses of translucent, yellowish matter, generally more [page 436] or less globular, or fine granules. In distant parts of the same bladder, the processes were transparent and quite empty, with the exception of their solid nuclei. My son made at short intervals of time sketches of one of the above aggregated masses, and found that they continually and completely changed their forms; sometimes separating from one another and again coalescing. Evidently protoplasm had been generated by the absorption of some element from the decaying animal matter.
(2) Another bladder included a still smaller speck of decayed brown matter, and the adjoining quadrifids contained aggregated matter, exactly as in the last case.
(3) A third bladder included a larger organism, which was so much decayed that I could only make out that it was spinose or hairy. The quadrifids in this case were not much affected, excepting that the nuclei in the several arms differed much in size; some of them containing two masses having a similar appearance.
(4) A fourth bladder contained an articulate organism, for I distinctly saw the remnant of a limb, terminating in a hook. The quadrifids were not examined.
(5) A fifth included much decayed matter apparently of some animal, but with no recognisable features. The quadrifids in contact contained numerous spheres of protoplasm.
(6) Some few bladders on the plant which I received from Kew were examined; and in one, there was a worm-shaped animal very little decayed, with a distinct remnant of a similar one greatly decayed. Several of the arms of the processes in contact with these remains contained two spherical masses, like the single solid nucleus which is properly found in each arm. In another bladder there was a minute grain of quartz, reminding me of two similar cases with Utricularia neglecta.
As it appeared probable that this plant would capture a greater number of animals in its native country than under culture, I obtained permission to remove small portions of the rhizomes from dried specimens in the herbarium at Kew. I did not at first find out that it was advisable to soak the rhizomes for two or three days, and that it was necessary to open the bladders and spread out their contents on glass; as from their state of decay and from having been dried and pressed, their nature could not otherwise be well distinguished. Several bladders on a plant which had grown in black earth in New Granada were first examined; and four of these included remnants of animals. The first contained a hairy Acarus, so much decayed that nothing was left except its transparent coat; [page 437] also a yellow chitinous head of some animal with an internal fork, to which the oesophagus was suspended, but I could see no mandibles; also the double hook of the tarsus of some animal; also an elongated greatly decayed animal; and lastly, a curious flask-shaped organism, having the walls formed of rounded cells. Professor Claus has looked at this latter organism, and thinks that it is the shell of a rhizopod, probably one of the Arcellidae. In this bladder, as well as in several others, there were some unicellular Algae, and one multicellular Alga, which no doubt had lived as intruders.
A second bladder contained an Acarus much less decayed than the former one, with its eight legs preserved; as well as remnants of several other articulate animals. A third bladder contained the end of the abdomen with the two hinder limbs of an Acarus, as I believe. A fourth contained remnants of a distinctly articulated bristly animal, and of several other organisms, as well as much dark brown organic matter, the nature of which could not be made out.
Some bladders from a plant, which had lived as an epiphyte in Trinidad, in the West Indies, were next examined, but not so carefully as the others; nor had they been soaked long enough. Four of them contained much brown, translucent, granular matter, apparently organic, but with no distinguishable parts. The quadrifids in two were brownish, with their contents granular; and it was evident that they had absorbed matter. In a fifth bladder there was a flask-shaped organism, like that above mentioned. A sixth contained a very long, much decayed, worm-shaped animal. Lastly, a seventh bladder contained an organism, but of what nature could not be distinguished.]
Only one experiment was tried on the quadrifid processes and glands with reference to their power of absorption. A bladder was punctured and left for 24 hrs. in a solution of one part of urea to 437 of water, and the quadrifid and bifid processes were found much affected. In some arms there was only a single symmetrical globular mass, larger than the proper nucleus, and consisting of yellowish matter, generally translucent but sometimes granular; in others there were two masses of different sizes, one large and the [page 438] other small; and in others there were irregularly shaped globules; so that it appeared as if the limpid contents of the processes, owing to the absorption of matter from the solution, had become aggregated sometimes round the nucleus, and sometimes into separate masses; and that these then tended to coalesce. The primordial utricle or protoplasm lining the processes was also thickened here and there into irregular and variously shaped specks of yellowish translucent matter, as occurred in the case of Utricularia neglecta under similar treatment. These specks apparently did not change their forms.
The minute two-armed glands on the valve were also affected by the solution; for they now contained several, sometimes as many as six or eight, almost spherical masses of translucent matter, tinged with yellow, which slowly changed their forms and positions. Such masses were never observed in these glands in their ordinary state. We may therefore infer that they serve for absorption. Whenever a little water is expelled from a bladder containing animal remains (by the means formerly specified, more especially by the generation of bubbles of air), it will fill the cavity in which the valve lies; and thus the glands will be able to utilise decayed matter which otherwise would have been wasted.
Finally, as numerous minute animals are captured by this plant in its native country and when cultivated, there can be no doubt that the bladders, though so small, are far from being in a rudimentary condition; on the contrary, they are highly efficient traps. Nor can there be any doubt that matter is absorbed from the decayed prey by the quadrifid and bifid processes, and that protoplasm is thus generated. What tempts animals of such diverse kinds to enter [page 439] the cavity beneath the bowed antennæ, and then force their way through the little slit-like orifice between the valve and collar into the bladders filled with water, I cannot conjecture.
Tubers.—These organs, one of which is represented in a previous figure (fig. 26) of the natural size, deserve a few remarks. Twenty were found on the rhizomes of a single plant, but they cannot be strictly counted; for, besides the twenty, there were all possible gradations between a short length of a rhizome just perceptibly swollen and one so much swollen that it might be doubtfully called a tuber. When well developed, they are oval and symmetrical, more so than appears in the figure. The largest which I saw was 1 inch (25.4 mm.) in length and .45 inch (11.43 mm.) in breadth. They commonly lie near the surface, but some are buried at the depth of 2 inches. The buried ones are dirty white, but those partly exposed to the light become greenish from the development, of chlorophyll in their superficial cells. They terminate in a rhizome, but this sometimes decays and drops off . They do not contain any air, and they sink in water; their surfaces are covered with the usual papillae. The bundle of vessels which runs up each rhizome, as soon as it enters the tuber, separates into three distinct bundles, which reunite at the opposite end. A rather thick slice of a tuber is almost as translucent as glass, and is seen to consist of large angular cells, full of water and not containing starch or any other solid matter. Some slices were left in alcohol for several days, but only a few extremely minute granules of matter were precipitated on the walls of the cells; and these were much smaller and fewer than those precipitated on the cell-walls of the rhizomes and bladders. We may therefore con- [page 440] clude that the tuber do not serve as reservoirs for food, but for water during the dry season to which the plant is probably exposed. The many little bladders filled with water would aid towards the same end.
To test the correctness of this view, a small plant, growing in light peaty earth in a pot (only 4 1/2 by 4 1/2 inches outside measure) was copiously watered, and then kept without a drop of water in the hothouse. Two of the upper tubers were beforehand uncovered and measured, and then loosely covered up again. In a fortnight’s time the earth in the pot appeared extremely dry; but not until the thirty-fifth day were the leaves in the least affected; they then became slightly reflexed, though still soft and green. This plant, which bore only ten tubers, would no doubt have resisted the drought for even a longer time, had I not previously removed three of the tubers and cut off several long rhizomes. When, on the thirty-fifth day, the earth in the pot was turned out, it appeared as dry as the dust on a road. All the tubers had their surfaces much wrinkled, instead of being smooth and tense. They had all shrunk, but I cannot say accurately how much; for as they were at first symmetrically oval, I measured only their length and thickness; but they contracted in a transverse line much more in one direction than in another, so as to become greatly flattened. One of the two tubers which had been measured was now three-fourths of its original length, and two-thirds of its original thickness in the direction in which it had been measured, but in another direction only one- third of its former thickness. The other tuber was one-fourth shorter, one-eighth less thick in the direction in which it had been measured, and only half as thick in another direction.
A slice was cut from one of these shrivelled tubers [page 441] and examined. The cells still contained much water and no air, but they were more rounded or less angular than before, and their walls not nearly so straight; it was therefore clear that the cells had contracted. The tubers, as long as they remain alive, have a strong attraction for water; the shrivelled one, from which a slice had been cut, was left in water for 22 hrs. 30 m., and its surface became as smooth and tense as it originally was. On the other hand, a shrivelled tuber, which by some accident had been separated from its rhizome, and which appeared dead, did not swell in the least, though left for several days in water.
With many kinds of plants, tubers, bulbs, &c. no doubt serve in part as reservoirs for water, but I know of no case, besides the present one, of such organs having been developed solely for this purpose. Prof. Oliver informs me that two or three species of Utricularia are provided with these appendages; and the group containing them has in consequence received the name of orchidioides. All the other species of Utricularia, as well as of certain closely related genera, are either aquatic or marsh plants; therefore, on the principle of nearly allied plants generally having a similar constitution, a never failing supply of water would probably be of great importance to our present species. We can thus understand the meaning of the development of its tubers, and of their number on the same plant, amounting in one instance to at least twenty.
UTRICULARIA NELUMBIFOLIA, AMETHYSTINA, GRIFFITHII, CAERULEA, ORBICULATA, MULTICAULIS.
As I wished to ascertain whether the bladders on the rhizomes of other species of Utricularia, and of the [page 442] species of certain closely allied genera, had the same essential structure as those of Utricularia montana, and whether they captured prey, I asked Prof. Oliver to send me fragments from the herbarium at Kew. He kindly selected some of the most distinct forms, having entire leaves, and believed to inhabit marshy ground or water. My son Francis Darwin, examined them, and has given me the following observations; but it should be borne in mind that it is extremely difficult to make out the structure of such minute and delicate objects after they have been dried and pressed.*
Utricularia nelumbifolia (Organ Mountains, Brazil).—The habitat of this species is remarkable. According to its discoverer, Mr. Gardner,** it is aquatic, but “is only to be found growing in the water which collects in the bottom of the leaves of a large Tillandsia, that inhabits abundantly an arid rocky part of the mountain, at an elevation of about 5000 feet above the level of the sea. Besides the ordinary method by seed, it propagates itself by runners, which it throws out from the base of the flower-stem; this runner is always found directing itself towards the nearest Tillandsia, when it inserts its point into the water and gives origin to a new plant, which in its turn sends out another shoot. In this manner I have seen not less than six plants united.” The bladders resemble those of Utricularia montana in all essential respects, even to the presence of a few minute two-armed glands on the valve. Within one bladder there was the remnant of the abdomen of some larva or crustacean of large size,
* Prof. Oliver has given (‘Proc. Linn. Soc.’ vol. iv. p. 169) figures of the bladders of two South American species, namely Utricularia Jamesoniana and peltata; but he does not appear to have paid particular attention to these organs.
** ‘Travels in the Interior of Brazil, 1836-41,’ p. 527. [page 443]
having a brush of long sharp bristles at the apex. Other bladders included fragments of articulate animals, and many of them contained broken pieces of a curious organism, the nature of which was not recognised by anyone to whom it was shown.
Utricularia amethystina (Guiana).—This species has small entire leaves, and is apparently a marsh plant; but it must grow in places where crustaceans exist, for there were two small species within one of the bladders. The bladders are nearly of the same shape as those of Utricularia montana, and are covered outside with the usual papillae; but they differ remarkably in the antennæ being reduced to two short points, united by a membrane hollowed out in the middle. This membrane is covered with innumerable oblong glands supported on long footstalks; most of which are arranged in two rows converging towards the valve. Some, however, are seated on the margins of the membrane; and the short ventral surface of the bladder, between the petiole and valve, is thickly covered with glands. Most of the heads had fallen off, and the footstalks alone remained; so that the ventral surface and the orifice, when viewed under a weak power, appeared as if clothed with fine bristles. The valve is narrow, and bears a few almost sessile glands. The collar against which the edge shuts is yellowish, and presents the usual structure. From the large number of glands on the ventral surface and round the orifice, it is probable that this species lives in very foul water, from which it absorbs matter, as well as from its captured and decaying prey.
Utricularia griffithii (Malay and Borneo).—The bladders are transparent and minute; one which was measured being only 28/1000 of an inch (.711 mm.) in diameter. The antennæ are of moderate length, and [page 444] project straight forward; they are united for a short space at their bases by a membrane; and they bear a moderate number of bristles or hairs, not simple as heretofore, but surmounted by glands. The bladders also differ remarkably from those of the previous species, as within there are no quadrifid, only bifid, processes. In one bladder there was a minute aquatic larva; in another the remains of some articulate animal; and in most of them grains of sand.
Utricularia caerulea (India).—The bladders resemble those of the last species, both in the general character of the antennæ and in the processes within being exclusively bifid. They contained remnants of entomostracan crustaceans.
Utricularia orbiculata (India).—The orbicular leaves and the stems bearing the bladders apparently float in water. The bladders do not differ much from those of the two last species. The antennæ, which are united for a short distance at their bases, bear on their outer surfaces and summits numerous, long, multicellular hairs, surmounted by glands. The processes within the bladders are quadrifid, with the four diverging arms of equal length. The prey which they had captured consisted of entomostracan crustaceans.
Utricularia multicaulis (Sikkim, India, 7000 to 11,000 feet).—The bladders, attached to rhizomes, are remarkable from the structure of the antennæ. These are broad, flattened, and of large size; they bear on their margins multicellular hairs, surmounted by glands. Their bases are united into a single, rather narrow pedicel, and they thus appear like a great digitate expansion at one end of the bladder. Internally the quadrifid processes have divergent arms of equal length. The bladders contained remnants of articulate animals. [page 445]
POLYPOMPHOLYX.
This genus, which is confined to Western Australia, is characterised by having a “quadripartite calyx.” In other respects, as Prof. Oliver remarks,* “it is quite a Utricularia.”
Polypompholyx multifida.—The bladders are attached in whorls round the summits of stiff stalks. The two antennæ are represented by a minute membranous fork, the basal part of which forms a sort of hood over the orifice. This hood expands into two wings on each side of the bladder. A third wing or crest appears to be formed by the extension of the dorsal surface of the petiole; but the structure of these three wings could not be clearly made out, owing to the state of the specimens. The inner surface of the hood is lined with long simple hairs, containing aggregated matter, like that within the quadrifid processes of the previously described species when in contact with decayed animals. These hairs appear therefore to serve as absorbents. A valve was seen, but its structure could not be determined. On the collar round the valve there are in the place of glands numerous one-celled papillae, having very short footstalks. The quadrifid processes have divergent arms of equal length. Remains of entomostracan crustaceans were found within the bladders.
Polypompholyx tenella.—The bladders are smaller than those of the last species, but have the same general structure. They were full of dbris, apparently organic, but no remains of articulate animals could be distinguished.
* ‘Proc. Linn. Soc.’ vol. iv. p. 171. [page 446]
GENLISEA.
This remarkable genus is technically distinguished from Utricularia, as I hear from Prof. Oliver, by having a five-partite calyx. Species are found in several parts of the world, and are said to be “herbae annuae paludosae.”
Genlisea ornata (Brazil).—This species has been described and figured by Dr. Warming,* who states that it bears two kinds of leaves, called by him spathulate and utriculiferous. The latter include cavities; and as these differ much from the bladders of the foregoing species, it will be convenient to speak of them as utricles. The accompanying figure (fig. 29) of one of the utriculiferous leaves, about thrice enlarged, will illustrate the following description by my son, which agrees in all essential points with that given by Dr. Warming. The utricle (b) is formed by a slight enlargement of the narrow blade of the leaf. A hollow neck (n), no less than fifteen times as long as the utricle itself, forms a passage from the transverse slit-like orifice (o) into the cavity of the utricle. A utricle which measured 1/36 of an inch (.705 mm.,) in its longer diameter had a neck 15/36 (10.583 mm.) in length, and 1/100 of an inch (.254 mm.) in breadth. On each side of the orifice there is a long spiral arm or tube (a); the structure of which will be best understood by the following illustration. Take a narrow ribbon and wind it spirally round a thin cylinder, so that the edges come into contact along its whole length; then pinch up the two edges so as to form a little crest, which will of course wind spirally
* “Bidrag til Kundskaben om Lentibulariaceae,” Copenhagen 1874. [page 447]
round the cylinder like a thread round a screw. If the cylinder is now removed, we shall have a tube like one of the spiral arms. The two projecting edges are not actually united, and a needle can be pushed in easily between them. They are indeed in many places a little separated, forming narrow entrances into the tube; but this may be the result of the drying of the specimens. The lamina of which the tube is formed seems to be a lateral prolongation of the lip of the orifice; and the spiral line between the two projecting edges is continuous with the corner of the orifice. If a fine bristle is pushed down one of the arms, it passes into the top of the hollow neck. Whether the arms are open or closed at their extremities could not be determined, as all the specimens were broken; nor does it appear that Dr. Warming ascertained this point.
FIG. 29. (Genlisea ornata.) Utriculiferous leaf; enlarged about three times. l Upper part of lamina of leaf. b Utricle or bladder. n Neck of utricle. o Orifice. a Spirally wound arms, with their ends broken off.
So much for the external structure. Internally the lower part of the utricle is covered with spherical papillae, formed of four cells (sometimes eight according to Dr. Warming), which evidently answer to the quadrifid processes within the bladders of Utricularia. [page 448] These papillae extend a little way up the dorsal and ventral surfaces of the utricle; and a few, according to Warming, may be found in the upper part. This upper region is covered by many transverse rows, one above the other, of short, closely approximate hairs, pointing downwards. These hairs have broad bases, and their tips are formed by a separate cell. They are absent in the lower part of the utricle where the papillae abound.
FIG. 30. (Genlisea ornata.) Portion of inside of neck leading into the utricle, greatly enlarged, showing the downward pointed bristles, and small quadrifid cells or processes.
The neck is likewise lined throughout its whole length with transverse rows of long, thin, transparent hairs, having broad bulbous (fig. 30) bases, with similarly constructed sharp points. They arise from little projecting ridges, formed of rectangular epidermic cells. The hairs vary a little in length, but their points generally extend down to the row next below; so that if the neck is split open and laid flat, the inner surface resembles a paper of pins,—the hairs representing the pins, and the little transverse ridges representing the folds of paper through which the pins are thrust. These rows of hairs are indicated in the previous figure (29) by numerous transverse lines crossing the neck. The inside of the neck is [page 449] also studded with papillae; those in the lower part are spherical and formed of four cells, as in the lower part of the utricle; those in the upper part are formed of two cells, which are much elongated downwards beneath their points of attachment. These two-celled papillae apparently correspond with the bifid process in the upper part of the bladders of Utricularia. The narrow transverse orifice (o, fig. 29) is situated between the bases of the two spiral arms. No valve could be detected here, nor was any such structure seen by Dr. Warming. The lips of the orifice are armed with many short, thick, sharply pointed, somewhat incurved hairs or teeth.
The two projecting edges of the spirally wound lamina, forming the arms, are provided with short incurved hairs or teeth, exactly like those on the lips. These project inwards at right angles to the spiral line of junction between the two edges. The inner surface of the lamina supports two-celled, elongated papillae, resembling those in the upper part of the neck, but differing slightly from them, according to Warming, in their footstalks being formed by prolongations of large epidermic cells; whereas the papillae within the neck rest on small cells sunk amidst the larger ones. These spiral arms form a conspicuous difference between the present genus and Utricularia.
Lastly, there is a bundle of spiral vessels which, running up the lower part of the linear leaf, divides close beneath the utricle. One branch extends up the dorsal and the other up the ventral side of both the utricle and neck. Of these two branches, one enters one spiral arm, and the other branch the other arm.
The utricles contained much dbris or dirty matter, which seemed organic, though no distinct organisms [page 450] could be recognised. It is, indeed, scarcely possible that any object could enter the small orifice and pass down the long narrow neck, except a living creature. Within the necks, however, of some specimens, a worm with retracted horny jaws, the abdomen of some articulate animal, and specks of dirt, probably the remnants of other minute creatures, were found. Many of the papillae within both the utricles and necks were discoloured, as if they had absorbed matter.
From this description it is sufficiently obvious how Genlisea secures its prey. Small animals entering the narrow orifice—but what induces them to enter is not known any more than in the case of Utricularia—would find their egress rendered difficult by the sharp incurved hairs on the lips, and as soon as they passed some way down the neck, it would be scarcely possible for them to return, owing to the many transverse rows of long, straight, downward pointing hairs, together with the ridges from which these project. Such creatures would, therefore, perish either within the neck or utricle; and the quadrifid and bifid papillae would absorb matter from their decayed remains. The transverse rows of hairs are so numerous that they seem superfluous merely for the sake of preventing the escape of prey, and as they are thin and delicate, they probably serve as additional absorbents, in the same manner as the flexible bristles on the infolded margins of the leaves of Aldrovanda. The spiral arms no doubt act as accessory traps. Until fresh leaves are examined, it cannot be told whether the line of junction of the spirally wound lamina is a little open along its whole course, or only in parts, but a small creature which forced its way into the tube at any point, would be prevented from escaping by the incurved hairs, and would find an open path down [page 451] the tube into the neck, and so into the utricle. If the creature perished within the spiral arms, its decaying remains would be absorbed and utilised by the bifid papillae. We thus see that animals are captured by Genlisea, not by means of an elastic valve, as with the foregoing species, but by a contrivance resembling an eel-trap, though more complex.
Genlisea africana (South Africa).—Fragments of the utriculiferous leaves of this species exhibited the same structure as those of Genlisea ornata. A nearly perfect Acarus was found within the utricle or neck of one leaf, but in which of the two was not recorded.
Genlisea aurea (Brazil).—A fragment of the neck of a utricle was lined with transverse rows of hairs, and was furnished with elongated papillae, exactly like those within the neck of Genlisea ornata. It is probable, therefore, that the whole utricle is similarly constructed.
Genlisea filiformis (Bahia, Brazil).—Many leaves were examined and none were found provided with utricles, whereas such leaves were found without difficulty in the three previous species. On the other hand, the rhizomes bear bladders resembling in essential character those on the rhizomes of Utricularia. These bladders are transparent, and very small, viz. Only 1/100 of an inch (.254 mm.) in length. The antennæ are not united at their bases, and apparently bear some long hairs. On the outside of the bladders there are only a few papillae, and internally very few quadrifid processes. These latter, however, are of unusually large size, relatively to the bladder, with the four divergent arms of equal length. No prey could be seen within these minute bladders. As the rhizomes of this species were furnished with bladders, those of Genlisea africana, ornata, and aurea were carefully [page 452] examined, but none could be found. What are we to infer from these facts? Did the three species just named, like their close allies, the several species of Utricularia, aboriginally possess bladders on their rhizomes, which they afterwards lost, acquiring in their place utriculiferous leaves? In support of this view it may be urged that the bladders of Genlisea filiformis appear from their small size and from the fewness of their quadrifid processes to be tending towards abortion; but why has not this species acquired utriculiferous leaves, like its congeners?
CONCLUSION.
It has now been shown that many species of Utricularia and of two closely allied genera, inhabiting the most distant parts of the world—Europe, Africa, India, the Malay Archipelago, Australia, North and South America—are admirably adapted for capturing by two methods small aquatic or terrestrial animals, and that they absorb the products of their decay.
Ordinary plants of the higher classes procure the requisite inorganic elements from the soil by means of their roots, and absorb carbonic acid from the atmosphere by means of their leaves and stems. But we have seen in a previous part of this work that there is a class of plants which digest and afterwards absorb animal matter, namely, all the Droseraceae, Pinguicula, and, as discovered by Dr. Hooker, Nepenthes, and to this class other species will almost certainly soon be added. These plants can dissolve matter out of certain vegetable substances, such as pollen, seeds, and bits of leaves. No doubt their glands likewise absorb the salts of ammonia brought to them by the rain. It has also been shown that some other plants can absorb ammonia by [page 453] their glandular hairs; and these will profit by that brought to them by the rain. There is a second class of plants which, as we have just seen, cannot digest, but absorb the products of the decay of the animals which they capture, namely, Utricularia and its close allies; and from the excellent observations of Dr. Mellichamp and Dr. Canby, there can scarcely be a doubt that Sarracenia and Darlingtonia may be added to this class, though the fact can hardly be considered as yet fully proved. There is a third class of plants which feed, as is now generally admitted, on the products of the decay of vegetable matter, such as the bird’s-nest orchis (Neottia), &c. Lastly, there is the well-known fourth class of parasites (such as the mistletoe), which are nourished by the juices of living plants. Most, however, of the plants belonging to these four classes obtain part of their carbon, like ordinary species, from the atmosphere. Such are the diversified means, as far as at present known, by which higher plants gain their subsistence.
INDEX.
A.
Absorption by Dionaea, 295 — by Drosera, 17 — by Drosophyllum, 337 — by Pinguicula, 381 — by glandular hairs, 344 — by glands of Utricularia, 416, 421 — by quadrifids of Utricularia, 413, 421 — by Utricularia montana, 437
Acid, nature of, in digestive secretion of Drosera, 88 — present in digestive fluid of various species of Drosera, Dionaea, Drosophyllum, and Pinguicula, 278, 301, 339, 381
Acids, various, action of, on Drosera, 188 — of the acetic series replacing hydrochloric in digestion, 89 —, arsenious and chromic, action on Drosera, 185 —, diluted, inducing negative osmose, 197
Adder’s poison, action on Drosera, 206
Aggregation of protoplasm in Drosera, 38 — in Drosera induced by salts of ammonia, 43 — — caused by small doses of carbonate of ammonia, 145 — of protoplasm in Drosera, a reflex action, 242 — — in various species of Drosera, 278 — — in Dionaea, 290, 300
Aggregation of protoplasm in Drosophyllum, 337, 339 — — in Pinguicula, 370, 389 — — in Utricularia, 411, 415, 429, 430, 436
Albumen, digested by Drosera, 92 —, liquid, action on Drosera, 79
Alcohol, diluted, action of, on Drosera, 78, 216
Aldrovanda vesiculosa, 321 —, absorption and digestion by, 325 —, varieties of, 329
Algae, aggregation in fronds of, 65
Alkalies, arrest digestive process in Drosera, 94
Aluminium, salts of, action on Drosera, 184
Ammonia, amount of, in rain water, 172 —, carbonate, action on heated leaves of Drosera, 69 —, —, smallness of doses causing aggregation in Drosera, 145 —, —, its action on Drosera, 141 —, —, vapour of, absorbed by glands of Drosera, 142 —, —, smallness of doses causing inflection in Drosera, 145, 168 —, phosphate, smallness of doses causing inflection in Drosera, 153, 168 —, —, size of particles affecting Drosera, 173 —, nitrate, smallness of doses causing inflection in Drosera, 148, 168 —, salts of, action on Drosera, 136
Ammonia, salts of, their action affected by previous immersion in water and various solutions, 213 —, —, induce aggregation in Drosera, 43 —, various salts of, causing inflection in Drosera, 166
Antimony, tartrate, action on Drosera, 185
Areolar tissue, its digestion by Drosera, 102
Arsenious acid, action on Drosera, 185
Atropine, action on Drosera, 204
B.
Barium, salts of, action on Drosera, 183
Bases of salts, preponderant action of, on Drosera, 186
Basis, fibrous, of bone, its digestion by Drosera, 108
Belladonna, extract of, action on Drosera, 84
Bennett, Mr. A.W., on Drosera, 2 —, coats of pollen-grains not digested by insects, 117
Binz, on action of quinine on white blood-corpuscles, 201 —, on poisonous action of quinine on low organisms, 202
Bone, its digestion by Drosera, 105
Brunton, Lauder, on digestion of gelatine, 111 —, on the composition of casein, 115 —, on the digestion of urea, 124 —, — of chlorophyll, 126 —, — of pepsin, 124
Byblis, 343
C.
Cabbage, decoction of, action on Drosera, 83
Cadmium chloride, action on Drosera, 183
Caesium, chloride of, action on Drosera, 181
Calcium, salts of, action on Drosera, 182
Camphor, action on Drosera, 209
Canby, Dr., on Dionaea, 301, 310, 313 —, on Drosera filiformis, 281
Caraway, oil of, action on Drosera, 211
Carbonic acid, action on Drosera, 221 —, delays aggregation in Drosera, 59
Cartilage, its digestion by Drosera, 103
Casein, its digestion by Drosera, 114
Cellulose, not digested by Drosera, 125
Chalk, precipitated, causing inflection of Drosera, 32
Cheese, its digestion by Drosera, 116
Chitine, not digested by Drosera, 124
Chloroform, effects of, on Drosera, 217 —, —, on Dionaea, 304
Chlorophyll, grains of, in living plants, digested by Drosera, 126 —, pure, not digested by Drosera, 125
Chondrin, its digestion by Drosera, 112
Chromic acid, action on Drosera, 185
Cloves, oil of, action on Drosera, 212
Cobalt chloride, action on Drosera, 186
Cobra poison, action on Drosera, 206
Cohn, Prof., on Aldrovanda, 321 —, on contractile tissues in plants, 364 —, on movements of stamens of Compositae, 256 —, on Utricularia, 395
Colchicine, action on Drosera, 204
Copper chloride, action on Drosera, 185
Crystallin, its digestion by Drosera, 120
Curare, action on Drosera, 204
Curtis, Dr., on Dionaea, 301
D.
Darwin, Francis, on the effect of an induced galvanic current on Drosera, 37 —, on the digestion of grains of chlorophyll, 126 —, on Utricularia, 442
Delpino, on Aldrovanda, 321 —, on Utricularia, 395
Dentine, its digestion by Drosera, 106
Digestion of various substances by Dionaea, 301 — — by Drosera, 85 — — by Drosophyllum, 339 — — by Pinguicula, 381 —, origin of power of, 361
Digitaline, action on Drosera, 203
Dionaea muscipula, small size of roots, 286 —, structure of leaves, 287 —, sensitiveness of filaments, 289 —, absorption by, 295 —, secretion by, 295 —, digestion by, 301 —, effects on, of chloroform, 304 —, manner of capturing insects, 305 —, transmission of motor impulse, 313 —, re-expansion of lobes, 318
Direction of inflected tentacles of Drosera, 243
Dohrn, Dr., on rhizocephalous crustaceans, 357
Donders, Prof., small amount of atropine affecting the iris of the dog, 172
Dragonfly caught by Drosera, 2
Drosera anglica, 278 — binata, vel dichotoma, 281 — capensis, 279 — filiformis, 281 — heterophylla, 284 — intermedia, 279
Drosera rotundifolia, structure of leaves, 4 —, effects on, of nitrogenous fluids, 76 Drosera rotundifolia, effects of heat on, 66 —, its power of digestion, 85 —, backs of leaves not sensitive, 231 —, transmission of motor impulse, 234 —, general summary, 262 — spathulata, 280
Droseraceae, concluding remarks on, 355 —, their sensitiveness compared with that of animals, 366
Drosophyllum, structure of leaves, 333 —, secretion by, 334 —, absorption by, 337 —, digestion by, 339
E.
Enamel, its digestion by Drosera, 106
Erica tetralix, glandular hairs of, 351
Ether, effects of, on Drosera, 219 —, —, on Dionaea, 304
Euphorbia, process of aggregation in roots of, 63
Exosmose from backs of leaves of Drosera, 231
F.
Fat not digested by Drosera, 126
Fayrer, Dr., on the nature of cobra poison, 206 —, on the action of cobra poison on animal protoplasm, 208 —, on cobra poison paralysing nerve centres, 224
Ferment, nature of, in secretion of Drosera, 94, 97
Fibrin, its digestion by Drosera, 100
Fibro-cartilage, its digestion by Drosera, 104
Fibro-elastic tissue, not digested by Drosera, 122
Fibrous basis of bone, its digestion by Drosera, 108
Fluids, nitrogenous, effects of, on Drosera, 76
Fournier, on acids causing movements in stamens of Berberis, 196
Frankland, Prof., on nature of acid in secretion of Drosera, 88
G.
Galvanism, current of, causing inflection of Drosera, 37 —, effects of, on Dionaea, 318
Gardner, Mr., on Utricularia nelumbifolia, 442
Gelatin, impure, action on Drosera, 80 —, pure, its digestion by Drosera, 110
Genlisea africana, 451 — filiformis, 451
Genlisea ornata, structure of, 446 —, manner of capturing prey, 450
Glandular hairs, absorption by, 344 —, summary on, 353
Globulin, its digestion by Drosera, 120
Gluten, its digestion by Drosera, 117
Glycerine, inducing aggregation in Drosera, 52 —, action on Drosera, 212
Gold chloride, action on Drosera, 184
Gorup-Besanez on the presence of a solvent in seeds of the vetch, 362
Grass, decoction of, action on Drosera, 84
Gray, Asa, on the Droseraceae, 2
Groenland, on Drosera, 1, 5
Gum, action of, on Drosera, 77
Gun-cotton, not digested by Drosera, 125
H.
Haematin, its digestion by Drosera, 121
Hairs, glandular, absorption by, 344 —, —, summary on, 353
Heat, inducing aggregation in Drosera, 53 —, effect of, on Drosera, 66 —, —, on Dionaea, 294, 319
Heckel, on state of stamens of Berberis after excitement, 43
Hofmeister, on pressure arresting movements of protoplasm, 61
Holland, Mr., on Utricularia, 395
Hooker, Dr., on carnivorous plants, 2 —, on power of digestion by Nepenthes, 97 —, history of observations on Dionaea, 286
Hydrocyanic acid, effects of, on Dionaea, 305
Hyoscyamus, action on Drosera, 84, 206
I.
Iron chloride, action on Drosera, 185
Isinglass, solution of, action on Drosera, 80
J.
Johnson, Dr., on movement of flower-stems of Pinguicula, 381
K.
Klein, Dr., on microscopic character of half digested bone, 106 —, on state of half digested fibro-cartilage, 104 —, on size of micrococci, 173
Knight, Mr., on feeding Dionaea, 301
Kossmann, Dr., on rhizocephalous crustaceans, 357
L.
Lead chloride, action on Drosera, 184
Leaves of Drosera, backs of, not sensitive, 231
Legumin, its digestion by Drosera, 116
Lemna, aggregation in leaves of, 64
Lime, carbonate of, precipitated, causing inflection of Drosera, 32 —, phosphate of, its action on Drosera, 109
Lithium, salts of, action on Drosera, 181
M.
Magnesium, salts of, action on Drosera, 182
Manganese chloride, action on Drosera, 185
Marshall, Mr. W., on Pinguicula, 369
Means of movement in Dionaea, 313 — in Drosera, 254
Meat, infusion of, causing aggregation in Drosera, 51 —, —, action on Drosera, 79 —, its digestion by Drosera, 98
Mercury perchloride, action on Drosera, 183
Milk, inducing aggregation in Drosera, 51 —, action on Drosera, 79 —, its digestion by Drosera, 113
Mirabilis longiflora, glandular hairs of, 352
Moggridge, Traherne, on acids injuring seeds, 128
Moore, Dr., on Pinguicula, 390
Morphia acetate, action on Drosera, 205
Motor impulse in Drosera, 234, 258 — in Dionaea, 313
Movement, origin of power of, 363
Movements of leaves of Pinguicula, 371 — of tentacles of Drosera, means of, 254 — of Dionaea, means of, 313
Mucin, not digested by Drosera, 122
Mucus, action on Drosera, 80
Müller, Fritz, on rhizocephalous crustaceans, 357
N.
Nepenthes, its power of digestion, 97
Nickel chloride, action on Drosera, 186
Nicotiana tabacum, glandular hairs of, 352
Nicotine, action on Drosera, 203
Nitric ether, action on Drosera, 220
Nitschke, Dr., references to his papers on Drosera, 1 —, on sensitiveness of backs of leaves of Drosera, 231 —, on direction of inflected tentacles in Drosera, 244 —, on Aldrovanda, 322
Nourishment, various means of, by plants, 452
Nuttall, Dr., on re-expansion of Dionaea, 318
O.
Odour of pepsin, emitted from leaves of Drosera, 88
Oil, olive, action of, on Drosera, 78, 126
Oliver, Prof., on Utricularia, 432, 441-446
P.
Papaw, juice of, hastening putrefaction, 411
Particles, minute size of, causing inflection in Drosera, 27, 32
Peas, decoction of, action on Drosera, 82
Pelargonium zonale, glandular hairs of, 350
Pepsin, odour of, emitted from Drosera leaves, 88 —, not digested by Drosera, 123 —, its secretion by animals excited only after absorption, 129
Peptogenes, 129
Pinguicula grandiflora, 390 — lusitanica, 391
Pinguicula vulgaris, structure of leaves and roots, 368 —, number of insects caught by, 369 —, power of movement, 371 —, secretion and absorption by, 381 —, digestion by, 381 —, effects of secretion on living seeds, 390
Platinum chloride, action on Drosera, 186
Poison of cobra and adder, their action on Drosera, 206
Pollen, its digestion by Drosera, 117
Polypompholyx, structure of, 445
Potassium, salts of, inducing aggregation in Drosera, 50 —, —, action on Drosera, 179 — phosphate, not decomposed by Drosera, 180, 187
Price, Mr. John, on Utricularia, 429
Primula sinensis, glandular hairs of, 348 —, number of glandular hairs of, 355
Protoplasm, aggregation of, in Drosera, 38 —, —, in Drosera, caused by small doses of carbonate of ammonia, 145 —, —, in Drosera, a reflex action, 242 — aggregated, re-dissolution of, 53 —, aggregation of, in various species of Drosera, 278 —, —, in Dionaea, 290, 300 —, —, in Drosophyllum, 337, 339 —, —, in Pinguicula, 370, 389 —, —, in Utricularia, 411, 415, 429, 430, 436
Q.
Quinine, salts of, action on Drosera, 201
R.
Rain-water, amount of ammonia in, 172
Ralfs, Mr., on Pinguicula, 390
Ransom, Dr., action of poisons on the yolk of eggs, 225
Re-expansion of headless tentacles of Drosera, 229 — of tentacles of Drosera, 260 — of Dionaea, 318
Roots of Drosera, 18 — of Drosera, process of aggregation in, 63 — of Drosera, absorb carbonate of ammonia, 141 — of Dionaea, 286 — of Drosophyllum, 332 — of Pinguicula, 369
Roridula, 342
Rubidium chloride, action on Drosera, 181
S.
Sachs, Prof., effects of heat on protoplasm, 66, 70 —, on the dissolution of proteid compounds in the tissues of plants, 362
Saliva, action on Drosera, 80
Salts and acids, various, effects of, on subsequent action of ammonia, 214
Sanderson, Burdon, on coagulation of albumen from heat, 74 —, on acids replacing hydrochloric in digestion, 89 —, on the digestion of fibrous basis of bone, 108 —, — of gluten, 118 —, — of globulin, 120 —, — of chlorophyll, 126 —, on different effect of sodium and potassium on animals, 187 —, on electric currents in Dionaea, 318
Saxifraga umbrosa, glandular hairs of, 345
Schiff, on hydrochloric acid dissolving coagulated albumen, 86 —, on manner of digestion of albumen, 93 —, on changes in meat during digestion, 99 —, on the coagulation of milk, 114 —, on the digestion of casein, 116 —, — of mucus, 123 —, on peptogenes, 129
Schloesing, on absorption of nitrogen by Nicotiana, 352
Scott, Mr., on Drosera, 1
Secretion of Drosera, general account of, 13 — —, its antiseptic power, 15 — —, becomes acid from excitement, 86 — —, nature of its ferment, 94, 97 — by Dionaea, 295 — by Drosophyllum, 335 — by Pinguicula, 381
Seeds, living, acted on by Drosera, 127 —, —, acted on by Pinguicula, 385, 390
Sensitiveness, localisation of, in Drosera, 229 — of Dionaea, 289 — of Pinguicula, 371
Silver nitrate, action on Drosera, 181
Sodium, salts of, action on Drosera, 176 —, —, inducing aggregation in Drosera, 50
Sondera heterophylla, 284
Sorby, Mr., on colouring matter of Drosera, 5
Spectroscope, its power compared with that of Drosera, 170
Starch, action of, on Drosera, 78, 126
Stein, on Aldrovanda, 321
Strontium, salts of, action on Drosera, 183
Strychnine, salts of, action on Drosera, 199
Sugar, solution of, action of, on Drosera, 78 —, —, inducing aggregation in Drosera, 51
Sulphuric ether, action on Drosera, 219 —, — on Dionaea, 304
Syntonin, its action on Drosera, 102
T.
Tait, Mr., on Drosophyllum, 332
Taylor, Alfred, on the detection of minute doses of poisons, 170
Tea, infusion of, action on Drosera, 78
Tentacles of Drosera, move when glands cut of, 36, 229 —, inflection, direction of, 243 —, means of movement, 254 —, re-expansion of, 260
Theine, action on Drosera, 204
Tin chloride, action on Drosera, 185
Tissue, areolar, its digestion by Drosera, 102 —, fibro-elastic, not digested by Drosera, 122
Tissues through which impulse is transmitted in Drosera, 247 — — in Dionaea, 313
Touches repeated, causing inflection in Drosera, 34
Transmission of motor impulse in Drosera, 234 — — in Dionaea, 313
Traube, Dr., on artificial cells, 216
Treat, Mrs., on Drosera filiformis, 281 —, on Dionaea, 311 —, on Utricularia, 408, 430
Trcul, on Drosera, 1, 5
Tubers of Utricularia montana, 439
Turpentine, action on Drosera, 212
U.
Urea, not digested by Drosera, 124
Urine, action on Drosera, 79
Utricularia clandestina, 430 — minor, 429
Utricularia montana, structure of bladders, 431 —, animals caught by, 435 —, absorption by, 437 —, tubers of, serving as reservoirs, 439
Utricularia neglecta, structure of bladders, 397 —, animals caught by, 405 —, absorption by, 413 —, summary on absorption, 421 —, development of bladders, 424
Utricularia, various species of, 441
Utricularia vulgaris, 428
V.
Veratrine, action on Drosera, 204
Vessels in leaves of Drosera, 247 — of Dionaea, 314
Vogel, on effects of camphor on plants, 209
W.
Warming, Dr., on Drosera, 2, 6 —, on roots of Utricularia, 397 —, on trichomes, 359 —, on Genlisea, 446 —, on parenchymatous cells in tentacles of Drosera, 252
Water, drops of, not causing inflection in Drosera, 35 —, its power in causing aggregation in Drosera, 52 —, its power in causing inflection in Drosera, 139 — and various solutions, effects of, on subsequent action of ammonia, 213
Wilkinson, Rev., on Utricularia, 398
Z.
Ziegler, his statements with respect to Drosera, 23 —, experiments by cutting vessels of Drosera, 249
Zinc chloride, action on Drosera, 184