Category: Science - Biology
Nearly one half of them are repetitions, mostly altered in scale and simplified in execution, of figures, or parts of figures, contained in the works of various Botanists and Zoologists. Among the authors whom I have laid under contribution, I may name Berkeley, Carpenter, Cuv...
Nearly one half of them are repetitions, mostly altered in scale and simplified in execution, of figures, or parts of figures, contained in the works of various Botanists and Zo...
2. PART IV.--MORPHOLOGICAL DEVELOPMENT.3. PART V.--PHYSIOLOGICAL DEVELOPMENT.4. PART VI.--LAWS OF MULTIPLICATION.5. CHAPTER I.§ 175. The division of Morphology from Physiology, is one which may be tolerably-well preserved so long as we do not carry our inquiries beyond the empirical generalizations of...
6. CHAPTER II.§ 180. Evolution implies insensible modifications and gradual transitions, which render definition difficult--which make it impossible to separate absolutely the phases of organ...
7. CHAPTER III.§ 187. That advanced composition arrived at in the _Archegoniatæ_, is carried still further in the Flowering Plants. In these most-elevated vegetal forms, aggregation of the thi...
8. CHAPTER IV.§ 199. What was said in § 180, respecting the ultimate structure of organisms, holds more manifestly of animals than of plants. That throughout the vegetal kingdom the cell is t...
9. CHAPTER V.§ 208. Insects, Arachnids, Crustaceans, and Myriapods, are all members of that higher division of the _Annulosa_[26] called _Articulata_ or now more generally _Arthropoda_. Thou...
10. CHAPTER VI.§ 212. While, in the course of their evolution, plants and animals have displayed progressive integrations, there have at the same time gone on progressive differentiations of t...
11. CHAPTER VII.§ 217. Among protophytes those exemplified by _Pleurococcus vulgaris_ are by general consent considered the simplest. As shown in Fig. 1, they are globular cells presenting no o...
12. CHAPTER VIII.§ 221. Aggregates of the first order supply a few examples of forms ramified in an approximately-regular manner, under conditions which subject their parts to approximately-regu...
13. CHAPTER IX.§ 228. Next in the descending order of composition come compound leaves. The relative sizes and distributions of their leaflets, as affecting their forms as wholes, have to be c...
14. CHAPTER X.§ 232. Following an order like that of preceding chapters, let us first note a few typical facts respecting the forms of clusters of flowers, apart from the forms of the flowers...
15. CHAPTER XI.§ 237. We come now to aggregates of the lowest order. Already something has been said (§ 217) concerning the forms of those morphological units which exist as independent plants...
16. CHAPTER XII.§ 238. Besides the more special causes of modification in the shapes of plants and of their parts, certain more general causes must be briefly noticed. These may be described as...
17. CHAPTER XIII.§ 242. The general considerations which preluded our inquiry into the shapes of plants and their parts, equally serve, so far as they go, to prelude an inquiry into the shapes o...
18. CHAPTER XIV.§ 244. Certain of the _Protozoa_ are quite indefinite in their shapes, and quite inconstant in those indefinite shapes which they have--the relations of their parts are indeterm...
19. CHAPTER XV.§ 254. When an elongated mass of any substance is transversely strained, different parts of the mass are exposed to forces of opposite kinds. If, for example, a bar of metal or...
20. CHAPTER XVI.§ 260. Among animals as among plants, the laws of morphological differentiation must be conformed to by the morphological units, as well as by the larger parts and by the wholes...
21. CHAPTER XVII.§ 262. That any formula should be capable of expressing a common character in the shapes of things so unlike as a tree and a cow, a flower and a centipede, is a remarkable fact;...
22. CHAPTER I.§ 265. The questions to be treated under the above title are widely different from those which it ordinarily expresses. We have no alternative, however, but to use Physiology in...
23. CHAPTER II.§ 268. The simplest plant presents a contrast between its peripheral substance and its central substance. In each protophyte, be it a spherical cell or a branched tube, or such...
24. CHAPTER III.§ 272. The motionless protococcoid forms of lower _Algæ_, which do not permanently expose any parts of their surfaces to actions unlike those which other parts are exposed to, h...
25. CHAPTER IV.§ 277. In passing from plants formed of threads or thin laminæ, to plants having some massiveness, we find that after the external and internal parts have become distinguished f...
26. CHAPTER V.Plants do not display integration in such distinct and multiplied ways as do animals. But its advance may be traced both directly and indirectly--directly in the increasing co-o...
27. CHAPTER VI.§ 287. What was said respecting the primary physiological differentiation in plants, applies with little beyond change of terms to animals. Among _Protozoa_, as among _Protophyt...
28. CHAPTER VII.§ 291. The outer tissues of animals, originally homogeneous over their whole surfaces, pass into a heterogeneity which fits their respective parts to their respective conditions...
29. CHAPTER VIII.§ 297. The change from the outside of the lips to their inside, introduces us to a new series of interesting and instructive facts, joining on to those with which the last chapt...
30. CHAPTER IX.§ 305. Physiological differentiation and physiological integration, are correlatives that vary together. We have but to recollect the familiar parallel between the division of l...
31. CHAPTER X.§ 310. Intercourse between each part and the particular conditions to which it is exposed, either habitually in the individual or occasionally in the race, thus appears to be th...
32. CHAPTER X^A.§ 314_a_. That from the beginning of life there has been an ever-increasing heterogeneity in the Earth’s Flora and Fauna, is a truth recognized by all biologists who accept the...
33. CHAPTER I.§ 315. If organisms have been evolved, their respective powers of multiplication must have been determined by natural causes. Grant that the countless specialities of structure...
34. CHAPTER II.§ 319. The number of a species must at any time be either decreasing or stationary or increasing. If, generation after generation, its members die faster than others are born, t...
35. CHAPTER III.§ 324. When dealing with its phenomena inductively, we saw that however it may be carried on, Genesis “is a process of negative or positive disintegration; and is thus essential...
36. CHAPTER IV.§ 329. Were all species subject to the same kinds and amounts of destructive forces, it would be easy, by comparing different species, to test the inverse variation of Individua...
37. CHAPTER V.§ 334. When illustrating, in Part IV, the morphological composition of plants and animals, there were set down in groups, numerous facts which we have here to look at from anoth...
38. CHAPTER VI.§ 338. In so far as it is a process of separation, sexual genesis is like asexual genesis; and is therefore, equally with asexual genesis, opposed to that aggregation which resu...
39. CHAPTER VII.§ 343. By Development, as here to be dealt with apart from Growth, is meant increase of structure as distinguished from increase of mass. As was pointed out in § 50, this is the...
40. CHAPTER VIII.§ 347. Under this head we have to set down no evidence derived from the vegetal kingdom. Plants are not expenders of force in such degrees as to affect the general relations wit...
41. CHAPTER IX.§ 352. Under this head may be grouped various facts which, in another way, tell the same tale as those contained in the last chapter. The evidence there put together went to sho...
42. CHAPTER X.§ 356. Tests of the general doctrines set forth in preceding chapters, are afforded by organisms having modes of life which diverge widely from ordinary modes. Here, as elsewher...
43. CHAPTER XI.§ 362. Considering the difficulties of inductive verification, we have, I think, as clear a correspondence between the _à priori_ and _à posteriori_ conclusions, as can be expec...
44. CHAPTER XII.§ 365. The relative fertility of Man considered as a species, and those changes in Man’s fertility which occur under changed conditions, must conform to the laws which we have t...
45. CHAPTER XIII.§ 371. Any further evolution in the most highly-evolved of terrestrial beings, Man, must be of the same nature as evolution in general. Structurally considered, it may consist i...