A586  (page sequence 338)   Book:     Lindley, John. 1853. The vegetable kingdom; or, the structure, classification, and uses of plants, illustrated upon the natural system. 3d ed. London: Bradbury & Evans.   Text   Image

approaching to black. It is to this stage or period that the descriptions of those authors who attribute a style and stigma to this genus apparently refer. Both Dr. Brown and Professor Lindley must likewise advert to this period when they state the nucleus to be surrounded with three envelopes. There can be no doubt, then, that in reality Gnetum is as truly naked-eeeded as Conifers themselves. Independently of the singular organisation of its ovule, the genus Gnetum is remarkable for some other

CUL-DAR138.2  (page sequence 3)   Printed:   Darwin Charles Robert  1855.00.00--1857.00.00   [All of DAR138.2 in one sequence of 173 images]   Text   Image

CMB iive fiattnito it turn out that some of the protozoa never develope ova or spermatozoa corresponding with those of the higher animals, we shall have to take the word ovum in the aphorism in as wide a sense as that in which Harvey employed it. But even in this case, so long as such ** prim-ordUum vegetale is invariably found to proceed from fanam similar to those which it produces, we shall be as £tf as crer from equivocal generation. The latter phrase is, in fact, intelligible in only two

CUL-DAR138.2  (page sequence 25)   Printed:   Darwin Charles Robert  1855.00.00--1857.00.00   [All of DAR138.2 in one sequence of 173 images]   Text   Image

the supporters of the doctrine of equivocal generation! Vox.. XXXIII. No. 8G8.-Xi:w SERIES, XO. 307. If it turn but that some of the protozoa never develops cither ova or spermatozoa corresponding with those of the higher animals, we shall have to take the word ** ovum in the aphorism in as wide a sense as that in which Harvey employed it. But even in this case, so long as such ** primordium vegetale is invariably found to proceed from forms similar to those which it produces, we shall be as

F373  (page sequence 460)   Book:     Darwin, C. R. 1859. On the origin of species by means of natural selection, or the preservation of favoured races in the struggle for life. London: John Murray. 1st edition, 1st issue.   Text   Image

fed by their parents or placed in the midst of proper nutriment, yet nearly all pass through a similar worm-like stage of development; but in some few cases, as in that of Aphis, if we look to the admirable drawings by Professor Huxley of the development of this insect, we see no trace of the vermiform stage. How, then, can we explain these several facts in embryology,—namely the very general, but not universal difference in structure between the embryo and the adult;—of parts in the same

A507  (page sequence 3)   Review:     Anon. 1859. Charles Darwin on the origin of species. Chambers's Journal 11: 388-391.   Text   Image

embryo and the adult; of parts in the same individual embryo, which ultimately become very unlike, and serve for diverse purposes, being at this early period of growth alike; of embryos of different species within the same class, generally, but not universally, resembling each other; of the structure of the embryo not being closely related to its conditions of existence, except when the embryo becomes at any period of life active, and has to provide for itself; of the embryo apparently having

CUL-DAR226  (page sequence 61)   Printed:   Darwin Charles Robert  1859.00.00--1882.00.00   [All of DAR226 in one sequence of 781 images] (Reviews of Darwin's works)   Text   Image

lately pubibbed by Messrs Famiutaiu aud IJoranetsky, respecting a similar differentiation in tbe gouidia of Licbens belonging to the gonera Physclo anu Cladouia It is, however, only certain of tbe gouidia which are so circumstanced: the contents of others simply divide into motionless globules A still more curious fact, if true, is that described by De Bary, after Clcnkowaky, in the division of Fungi kuown under tbe name of Myxogastres or false putfballs Their spores, when germinating, in certain

F376  (page sequence 460)   Book:     Darwin, C. R. 1860. On the origin of species by means of natural selection, or the preservation of favoured races in the struggle for life. London: John Murray. 2d edition, second issue.   Text   Image

adult: thus Owen has remarked in regard to cuttle-fish, there is no metamorphosis; the cephalopodic character is manifested long before the parts of the embryo are completed; and again in spiders, there is nothing worthy to be called a metamorphosis. The larvæ of insects, whether adapted to the most diverse and active habits, or quite inactive, being fed by their parents or placed in the midst of proper nutriment, yet nearly all pass through a similar worm-like stage of development; but in

F381  (page sequence 504)   Book:     Darwin, C. R. 1861. On the origin of species by means of natural selection, or the preservation of favoured races in the struggle for life. London: John Murray. 3d edition. Seventh thousand.   Text   Image

is no metamorphosis; the cephalopodic character is manifested long before the parts of the embryo are completed; and again in spiders, there is nothing worthy to be called a metamorphosis. The larvæ of insects, whether adapted to the most diverse and active habits, or quite inactive, being fed by their parents or placed in the midst of proper nutriment, yet nearly all pass through a similar worm-like stage of development; but in some few cases, as in that of Aphis, if we look to the admirable

F381  (page sequence 501)   Book:     Darwin, C. R. 1861. On the origin of species by means of natural selection, or the preservation of favoured races in the struggle for life. London: John Murray. 3d edition. Seventh thousand.   Text   Image

are in the embryo exactly alike. The embryos, also, of distinct animals within the same class are often strikingly similar: a better proof of this cannot be given, than a statement made by Von Baer, namely, that the embryos of mammalia, of birds, lizards, and snakes, probably also of chelonia, are in their earliest states exceedingly like one another, both as a whole and in the mode of development of their parts; so much so, in fact, that we can often distinguish the embryos only by their size

F877.2  (page sequence 354)   Book:     Darwin, C. R. 1868. The variation of animals and plants under domestication. London: John Murray. 1st edition, first issue. Volume 2   Text   Image

the expression of La loi de l'affinité de soi pour soi. It has been fully discussed and illustrated by his son, Isidore Geoffroy, with respect to monsters in the animal kingdom,1 and by Moquin-Tandon, with respect to monstrous plants. When similar or homologous parts, whether belonging to the same embryo or to two distinct embryos, are brought during an early stage of development into contact, they often blend into a single part or organ; and this complete fusion indicates some mutual affinity

F880.2  (page sequence 49)   Book:     Darwin, C. R. 1875. The variation of animals and plants under domestication. London: John Murray. 2d edition. Volume 2.   Text   Image

of lesser anomalies are admitted by every one to be due to an arrest of development, that is, to the persistence of an embryonic condition. But many monstrosities cannot be thus explained; for parts of which no trace can be detected in the embryo, but which occur in other members of the same class of animals occasionally appear, and these may probably with truth be attributed to reversion. As, however, I have treated this subject as fully as I could in my 'Descent of Man' (chap. i., 2nd edit

F1548.1  (page sequence 410)   Book:     Darwin, Francis & Seward, A. C. eds. 1903. More letters of Charles Darwin. A record of his work in a series of hitherto unpublished letters. London: John Murray. Volume 1   Text   Image

creatures of the simplest organisations mainly multiply by some process of self-division. 1. Mr. Galton's idea is that in a bud or other asexually produced part, the germs (i.e. gemmules) may not be completely representative of the whole organism, and if reproduction is continued asexually at each successive stage there is always a chance of some one or more of the various species of germs... dying out (page 333). Mr. Galton supposes, in sexual reproduction, where two parents contribute germs to the

A162  (page sequence 140)   Book:     Seward, A. C. ed. 1909. Darwin and modern science. Essays in commemoration of the centenary of the birth of Charles Darwin and of the fiftieth anniversary of the publication of The origin of species. Cambridge: Cambridge University Press.   Text   Image

formed, that is to those positions towards which the longitudinal halves of the chromosomes travel in ordinary nuclear divisions. It is clear that in this way the number of chromosomes which the daughter-nuclei contain, as the result of the first stage in division in the gonotokonts, will be reduced by one half, while in ordinary divisions the number of chromosomes always remains the same. The first stage in the division of the nucleus in the gonotokonts has therefore been termed the reduction

A162  (page sequence 208)   Book:     Seward, A. C. ed. 1909. Darwin and modern science. Essays in commemoration of the centenary of the birth of Charles Darwin and of the fiftieth anniversary of the publication of The origin of species. Cambridge: Cambridge University Press.   Text   Image

differ from each other in structure and habits in their adult condition, if they pass through closely similar embryonic stages, we may feel assured that they all are descended from one parent-form, and are therefore closely related. Thus, community in embryonic structure reveals community of descent; but dissimilarity in embryonic development does not prove discommunity of descent, for in one of two groups the developmental stages may have been suppressed, or may have been so greatly modified