Chapter 8

Among the matters of interest which were brought before the British Medical Association, at the recent Glasgow meeting, was an account by Mr. Brudenell Carter of a method which he had devised of opening the sheath of the optic nerve behind the eye, for the relief of pressure within this sheath and within the cavity of the skull. The brain is invested by firm membranes, which secrete a certain amount of fluid and are continued down to the eye in the form of a sheath which surrounds the optic nerve; and, whenever the pressure within the cavity of the skull is increased, as by the growth of a brain tumor, or even by excess of secretion from the membranes themselves, a superabundance of fluid is apt to find its way down the nerve sheath to the level of the eye, to subject the optic nerve to injurious pressure, and, in many cases, to destroy the sight. It not infrequently happens that the pressure within the brain cavity may be increased by temporary or curable causes, which, nevertheless, continue in action sufficiently long to produce permanent blindness, even although the patient may, in other respects, recover. In view of these conditions it was suggested by Dr. De Wecker, of Paris, sixteen or seventeen years ago, that it might be possible to open the optic nerve sheath, and thus not only to relieve the nerve from pressure and to preserve it from injury, but also, on account of the position of the eye relatively to the brain cavity, to drain the latter by gravitation, and to relieve the brain as well as the eye. Dr. De Wecker made two endeavors to accomplish this object, but he tried to feel his way to the optic nerve without the aid of sight, and to incise the sheath by means of an instrument carrying a concealed knife, capable of being projected by means of a spring. The risks of failure, and, still more, the risks of inflicting irreparable injury upon the nerve, were such that he only attempted his operation in two well nigh hopeless cases, and only one attempt to follow his example has been recorded. Mr. Carter's attention was called to the matter last year by a case in which the diminution of pressure within the optic nerve sheath was manifestly desirable; and he devised a method of operating by which the sheath could be exposed to view, and the object attained with certainty, under the guidance of sight at every step of the process.

He read before the Medical Society of London, last year, an account of the first case in which he operated, which was successful; and he read an account of three more cases at Glasgow, in one of which the result was negative, as far as sight was concerned, while in the other two the patients were not only quickly restored to useful vision, in one instance from complete, in the other from nearly complete, blindness, but were at the same time relieved or cured of other symptoms, such as headache and sickness, arising from direct pressure on the brain. In his paper at Glasgow, Mr. Carter claimed for the new operation that it could be performed with certainty and without risk either to life or to any important structure, and that it afforded a reasonable prospect of the preservation of sight in many forms of disease in which it is now habitually or frequently lost. As in the case of every new operation, time and further experience of its effects are required in order to determine the precise limits of its usefulness.

In the discussion which followed the paper, Mr. Bickerton, of Liverpool, said that, in consequence of reading the account of Mr. Carter's first case, he had himself performed the operation in two instances, in one of which temporary restoration of sight was followed by relapse, while in the second the ultimate issue was favorable.--_London Times._

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PUTZEYS' FLUSHING RESERVOIR.

Every sewer is more or less exposed to intermissions in the flow of the water that it leads, and the result is a diminution in velocity which leads to deposits of solid material. Hence the necessity of regularly flushing the sewer with water, which removes from the sides the substances that have attached themselves thereto, and which, without such precaution, soon decompose. In a word, it is necessary that a _perfect_ washing shall be assured, and this can be done only by heavy rains or by strong currents of water. As regards rain, that could not be relied upon; and to have a force of men specially charged with the service of washing, that would be too costly, and so recourse has been had to automatic apparatus.

The automatic siphons used for flushing sewers are characterized in general by the presence, at the base of the discharge branch, of a fixed or movable receiving vessel full of water. This vessel has the inconvenience of breaking the effect of the charge, and the result is that these apparatus do not render the services that might be expected from them. Some of these apparatus have valves, floats, chains, pulleys, and levers. These are still more defective, since their operation is delicate. The parts of which they are composed easily get out of order, and then the reservoir does no more flushing at all. A good automatic flushing reservoir must therefore be of the greatest simplicity, and its parts must be fixed and strong, and the outflow of the water must be rapid and energetic and directly from the reservoir into the sewer. In a word, its construction should be such that there shall be no need of inspecting it, and that its operation be regular.

The apparatus devised by Mr. E. Putzeys, Director of Works of the city of Verviers, well fulfills the conditions of an excellent flushing reservoir with an automatic siphon. The siphon has a double curve, but may, however, have different forms according to the various uses for which it may be employed, such as for flushing sewers, urinals, closets, etc.

The annexed figure represents the apparatus as arranged for flushing a sewer. The apparatus operates as follows: In the bottom of the branch of the siphon, S, there is always some water, so that, during the filling of the reservoir by means of the cock seen in the figure, the air is compressed in the branch S to a degree that cannot exceed the pressure of an equal height of water to about double the height of the siphon. The reservoir therefore can continue to fill without the water escaping.

The submersion of the small siphon, a, b, c, is less than that of the principal siphon, S, and it follows that when the level of the reservoir reaches a height equal to b, a, a new influx, however small it be, causes the discharge of a few drops of water from the auxiliary siphon, a, b, c, which is always full of water. At this moment the water that it contains can no longer resist the thrust of the compressed air in the branch of the siphon, S, and is therefore forced, along with the compressed air, into the flushing pipe.

By virtue of the principle of communicating vessels, the water of the reservoir tends to resume its level in the interior of the apparatus, and it then enters with such impetuosity that the siphon, whatever be its dimensions, is primed. The entire reservoir empties instantaneously, and the water flows to open the sewer.

From the experiments made at Verviers by the inventor, it results that, with a pipe 10 inches in diameter, the emptying of a 175 cubic foot reservoir can be effected in 30 seconds.

We may remark that with this apparatus we obtain the maximum of useful effect, seeing that the work developed is represented by the total head of the water diminished simply by losses of charge due to friction in the pipes. In other apparatus the loss of charge is much less, since the flushing is broken by a receiver.

Putzeys' apparatus, therefore, with a much less discharge of water, is capable of producing an effect superior to that of similar apparatus. On account of its simplicity and plain character, there is no need of precision in the installation of this apparatus, and horizontality, even, is not a _sine qua non_ for its perfect operation.

The siphon is very easily cleaned, and this is a great advantage, since it permits of utilizing sewage matter for filling the flushing reservoir.--_Chronique Industrielle._

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PEPSIN.

By A. PERCY SMITH, F.I.C., F.C.S., Rugby.

The method usually adopted for estimating the peptonizing power of pepsina porci consists in dissolving 1 to 2 grains in 8 to 12 ounces of water, to which 40 to 60 minims of hydrochloric acid has been added. 500 to 1,000 grains of hard-boiled white of egg, granulated by rubbing through a wire sieve, is immersed in the liquid, and the whole kept at 98° to 130° F. for four hours, when the undissolved albumen is filtered off through muslin, and, after partial drying, is weighed to ascertain the amount dissolved. The variable numbers above quoted embrace various formulæ recommended by different experimenters.

This method of analysis is excessively crude and untrustworthy. When hard-boiled white of egg is kept in warm water, it absorbs a considerable quantity of that menstruum, as much as several units per cent.; consequently, on weighing the residual albumen, you may find that the weight is greater instead of less than that with which you started, the gain in weight due to absorbed water more than counterbalancing the loss obtaining through solution, as has happened with indifferent samples of pepsin. Then who shall say when, by simple air drying, the albumen has regained its former condition? The enormous quantity of albumen is foreign to the usual habits of the scientific analyst, and involves an enormous waste of time in manipulation.

One trial of this method was enough for me. The first modification I adopted consisted in substituting for the large quantity of granulated albumen a single half of the white of an egg in one piece. I likewise arranged a check experiment in which the pepsin was omitted, other conditions remaining unaltered. At the end of four hours the residual pieces of albumen were placed on blotting paper to remove superfluous moisture, and weighed. The gain in weight of the albumen in the check experiment, due to absorbed water, was calculated into percentage, and the same deducted from the weights of the other portions which had been subjected to the action of various pepsins. This, although an improvement upon the old method, proved likewise unreliable, because the water absorbed was not equal in each experiment. The albumen which was immersed in acidulated water only quickly dried, superficially, when placed on blotting paper, whereas that which had been acted on by pepsin was rendered glutinous and incapable of being dried in this manner. In fact, one sample weighed considerably more than it did at starting, even after deducting the allowance for water absorbed.

I next tried much smaller pieces of albumen, about 1 c.c., in hope that complete solution might ensue, and a time value be obtained. I soon found, however, that the solubility does not depend upon the mass, but upon the surface exposed.

Finally I discarded altogether the use of fresh white of egg, and had recourse to dry powdered albumen, prepared by drying in a steam oven and levigation in a mortar. With this I succeeded in getting accurate comparisons between the digestive powers of various pepsins. Albumen in this form dissolves with rapidity, owing to its state of fine division. Any remaining undissolved can be filtered off on a counterpoised filter paper, and heated in a water oven until absolutely dry. It is, however, unnecessary to do this when two samples only are compared against each other, nor is it essential to know the actual weight of albumen employed, provided it be the same in each experiment. This is insured by placing some on the naked pan of the balance (there is no objection to so doing, as it is a dry gritty powder, and does not adhere to the metal), and counterpoising by a similar addition to the other pan.

Let the albumen fall on the center of the filtered liquid, avoiding, if possible, contact with the glass of the beaker. It soon sinks, and after the lapse of some time, a simple inspection will show which is dissolving with the greater rapidity. Agitation assists solution. Therefore take the two beakers, one in each hand, and rotate the contents equally. When one sample has dissolved all the albumen, it is manifestly superior to the other which has failed to do so in the given time. If many samples have to be compared, it will be necessary to start with known quantities of albumen, and weigh the undissolved residues in the manner above indicated.

An objection may possibly be raised to this modified method, viz., that albumen as ingested is not in the form of a dry powder, and that we ought to copy as nearly as possible the conditions existing in the stomach. To this I would reply that it does not matter in the least, to us, as analysts, what are the conditions which obtain in the stomach; since there is no absolute test for pepsin, we can only compare one sample against another, and that which dissolves the most albumen in the shortest time is taken to be the best.

Another imperfect method of analysis is that employed in the examination of malt extracts for diastase, in which a certain weight of extract ought to dissolve a certain weight of starch in ten minutes, when if it does so dissolve it, the extract is a good one; if not, it is to be condemned. The more correct way is to ascertain the reducing power on Fehling's solution, before and after digestion with an _excess_ of starch, and I intend to say a few words upon this subject on a future occasion, when I have ascertained the maximum amount of diastase existing in the best samples of malt.--_The Analyst._

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SUBTERRANEOUS FLORA AND FAUNA.

By Dr. OTTO ZACHARIAS.

It is generally correct to say that air, light and moisture form the chief conditions necessary for the development of organic plant or animal life. One of these conditions, however, namely light, is not of equal importance with the two others. For modern investigation and the discoveries made during the progress of natural sciences have shown that in the depths of the ocean, where an everlasting darkness reigns, and where the temperature is extremely low, nevertheless a great abundance of animal life is to be found, and that there exist living beings, not only of the lowest organization, but even fishes and crustaceans of very complicated structure, all of which thrive without enjoying the slightest ray of light.

A similar example of animal life in the absence of light is to be found in the fauna of caves and grottoes. This was first made known to the world by Austrian and American naturalists. The well known Adelsberg grotto in Krain, and the gigantic Mammoth Cave in Kentucky, furnished much interesting material for a detailed study of the biological conditions of subterraneous animal life. It was gradually discovered that in those dark places there existed not only insects, spiders, crustaceans, centipedes, worms, and snails, but also a kind of salamander and fishes. But what gave special interest to these discoveries was the fact, ascertained by careful study, that not all of these beings were gifted with normally developed organs of vision, but that in some these organs had undergone a retrograde development, while others were entirely blind.

Among the latter, the blind fish of the Mammoth Cave (_Amblyopsis spelacus_) is especially remarkable, because in this being the retrograde development of the organ of vision is accompanied by the production of certain ridges of skin on the body which are endowed with an extreme sensitiveness of touch, and which, according to a work lately published by Professor Von Leydig, are composed of little warts in which the nerve fibers end. Nature, therefore, has in this case compensated the amblyopsis for his loss of sight by endowing him with a highly developed organ of feeling.

A similar phenomenon is to be observed in the blind crab (_Cambaras pellucidus_), which is also found in the Mammoth Cave, for in this being, according to Professor Von Leydig, the little warts on the interior feelers, which constitute the organ of smell, have also received an abnormal development.

Better known than the blind fish and the blind crab of Kentucky is the _Proteus anguineus_, a kind of salamander, of a pale rose color, endowed with gills and found in the Adelsberg grotto in Austria. (Fig. 1.)

This amphibium has an eye which lies very deep in the body and is almost overgrown by the skin. But this eye is by no means as developed as the organ of vision, for instance, of the water salamander (the triton) or of the so-called axolotl, for it exists only in a kind of embryonic development, and contains neither a vitreous humor nor a lens for the refraction of the rays of light. As, however, the nerve of vision exists, it is possible that this salamander may be able to discern in some manner between light and darkness.

The thinking student, when discovering such imperfect organs of sight, will naturally ask how the eye of this salamander, which is so useless for its real purpose, has come into existence, and he will weigh the comparative value of the two following explanations. It may be assumed that there existed once in the Adelsberg grotto a salamander which was absolutely blind, and in which, in consequence of an innate power of evolution, an organ of vision of the lowest kind was gradually formed. But to this assumption the objection may be raised at once, why nature should have produced an organ of vision in an animal living in a grotto, where such an organ is absolutely useless, and where such a development would be quite as paradoxical and improbable as, for instance, the development of fins instead of legs in an animal living on dry land.

On the other hand, one may suppose, and this is the more probable explanation, that the _Proteus anguineus_ is descended from a kind of salamander, which possessed perfectly developed eyes in the beginning, and that the imperfect organ of vision in the descendants living in the dark caves is the result of gradual degeneration. This is the more likely to be true as in many other cases, also, we find that organs which become useless and cannot be employed have gradually degenerated.

Our common mole furnishes an example. Its eyes also have become small and are deeply hidden in the muscles, although they are by no means as much degenerated as in the _Proteus anguineus_, and are still possessed of a lens and a retina. Their nerve of vision, however, has become very imperfect, and its connection with the brain is interrupted, so that the animal for this reason can have no perception of light. Notwithstanding the above, however, it is doubtful whether the degeneration and gradual disappearance of the visual organ is in all cases the result of their being no longer employed, since there exists in dark caves a kind of beetle, the _Machaerites_, in which species the female only is blind, while the male has a well developed organ of sight. In this case it cannot be maintained that the absence of light has been the cause of the blindness of the female beetle, because it would have acted equally upon the male. Nevertheless, no other explanation can be found for the blindness. The problem, therefore, is hitherto unsolved.

Of late the investigations of naturalists have been extended to the animal life existing not only in grottoes and caves, but also in mines and pits created by the action of man, and this has led to many interesting discoveries and remarkable results. A naturalist who has especially enlarged our knowledge with regard to the subterraneous fauna and flora is Dr. Robert Schneider, of Berlin, who made his studies in the coal mines near Waldenburg and Altwasser, in Silesia, the salt mines of Stassfurt and the metal mines of Klausthal, in the Upper Harz Mountains.

As regards the subterraneous flora, Dr. Schneider's investigations resulted in showing that the plants which thrive in the dark regions under ground are those which possess no chlorophyl and are sensitive to light. Those which vegetate most luxuriantly there are the _fungi_, and among them especially the _pyrenomycetes_, which are frequent in the waters of mines. Their general aspect is shown in a 480 times magnified form in Fig. 2. They resemble fine threads of delicate structure, and where found are always discovered in great abundance. Most conspicuous by their shape and considerable size are the _rhizomorphæ_, Fig. 3a, and they are remarkable, not only for their brilliant phosphorescence, but also for the peculiar fact that they are only found in places where light does not enter. These _rhizomorphæ_, though this is not easily recognizable from their external appearance, also belong to the fungi and are often seen in strings of the length of over a meter and the thickness of a quill, spreading out in peculiar branches and hanging down from moist beams in dark places. Sometimes they grow like seaweed in the water of the mines, and in this case they give much embarrassment to the miners, because they are apt to obstruct the channels constructed for leading off the superfluous water. In the mines of Freiberg these _rhizomorphæ_ exist in great abundance, and Humboldt already mentions specimens of the length of 4½ feet. Miners in Germany call them _zwirn_ (thread). The student of natural sciences, when encountering these peculiar forms of vegetation, will ask in how far they are the product of their surrounding circumstances (i.e., of the absence of light or the presence of moisture), and in order to find a reply to this question experiments have been made to grow these _rhizomorphæ_ under different conditions of existence. These experiments have shown that from several species of _rhizomorphæ_ other ordinary fungi can be developed, and that the subterraneous specimens therefore may be considered a degeneration and variation of the fungi found above the surface of the ground.

In Fig. 4b the _Himantia villosa_ is represented, a rhizomorpha found in the mines of the Upper Harz Mountains, thus showing another form of this vegetable growth. Though it is difficult, as above stated, to recognize by their shape the rhizormorphæ as fungi, the origin of the peculiar _Agaricus myurus_ of Hoffmann (Fig. 4a) will be much easier discovered, though a retrograde development and degeneration has taken place also in this fungus. It still shows, however, the elements of a regular toadstool, only that the stem is much elongated and looks like a thread or a tube, while the cap is small, and this explains how, by gradual degeneration, the cap may disappear entirely, leaving nothing but a stem, as, for instance, in the case of the _Clavaria deflexa_, the club fungus, shown in Fig. 3b.

In connection with the above it may be well to speak of the fungi constituting the mould which often covers the roof and the doors in the brown-coal mines of Halle, specimens of which are shown in Fig. 5.