A Treatise on Comparative Embryology: VertebrataMacmillan, 1885 - 792 pages |
Autres éditions - Tout afficher
A Treatise on Comparative Embryology: Vertebrata Francis Maitland Balfour Affichage du livre entier - 1885 |
A Treatise on Comparative Embryology, Volume 2 Francis Maitland Balfour Affichage du livre entier - 1885 |
A Treatise on Comparative Embryology, Volume 2 Francis Maitland Balfour Affichage du livre entier - 1881 |
Expressions et termes fréquents
adult alimentary tract allantois amnion Amniota Amphibia Amphioxus aorta appears artery atrophy auditory becomes divided blastoderm blastopore body cavity brain branchial cartilage cartilaginous cells CHICK Chordata chorion connected continuous derived differentiation dorsal Elasmobranchii embryo epiblast epidermis epithelial epithelium external folds formation formed front ganglion Gegenbaur germinal gives rise gland Götte hyoid hypoblast inner invagination Kölliker larva larvæ lateral layer lens lobes longitudinal Mammalia mandibular arch medullary groove medullary plate membrane mesenteron mesoblast mid-brain mouth Müllerian duct muscle-plate nerve nervous system neural canal neurenteric neurenteric canal notochord olfactory opening optic vesicle origin outer outgrowth ovum peritoneal placenta posterior primitive streak probably pronephros region rudiment sack segmental duct segmental tubes segmentation cavity shew shewn side somites splanchnic stage structure surface tail Teleostei thickened tissue TRANSVERSE trunk types vascular vein ventral ventricle vertebral Vertebrata vide wall Wolffian duct yolk yolk-sack
Fréquemment cités
Page 201 - More or less similar relations are also well marked in the case of the goose and the fowl (Gasser),2 and support the conclusion deducible from the lower forms of vertebrata, that the notochord is essentially hypoblastic. The passage at the front end of the primitive streak forms the posterior boundary of the medullary plate, though the medullary groove is not at first continued back to it. The anterior wall of this passage connects together the medullary plate and the notochordal ridge of the hypoblast....
Page 446 - Kolliker, following Remak and other older embryologists, absolutely deny the fact. I feel quite sure that no one studying the development of the nerves in Elasmobranchii with well-preserved specimens could for a moment be doubtful on this point...
Page 678 - ... median division of the body-cavity by longitudinal septa of transverse muscles. Each fully developed organ consists of three parts: (1) A dilated vesicle opening externally at the base of a foot. (2) A coiled glandular tube connected with this, and subdivided again into several minor divisions. (3) A short terminal portion opening at one extremity into the coiled tube (2) and at the other, as I believe, into the body-cavity.
Page 229 - ... ventral body wall ; hh. pericardial cavity. network. The hinder end of the heart is continued into two vitelline veins, each of which divides into an anterior and a posterior branch. The anterior branch is a limb of the sinus terminalis, and the posterior and smaller branch is continued towards the hind part of the sinus, near which it ends. On its way it receives, on its outer side, numerous branches from the venous network. The venous network connects by its anastomoses, the posterior branch...
Page 336 - ... origin, can any valid arguments be produced to show that either of them reproduces the mode of passage between the Protozoa and the ancestral two-layered Metazoa. These conclusions do not, however, throw any doubt upon the fact that the gastrula, however evolved, was a primitive form of the Metazoa; since this conclusion is founded upon the actual existence of adult gastrula forms independently of their occurrence in development.
Page 128 - The external opening of this passage finally becomes obliterated, and the passage itself is left as a narrow diverticulum leading from the hind end of the mesenteron into the neural canal (fig. 76). It forms the post-anal gut, and gradually narrows and finally atrophies.
Page 412 - Balfour ('81, p. 344) confesses that he has "some doubts as to the complete accuracy " of the conclusions to which Foster and he had previously arrived ('74, p. 187). He thinks it probable that the dorsal fissure is a direct result of the atrophy of the dorsal part of the central canal. Dorsally the walls of the canal coalesce, and the fusion gradually proceeds ventralwards, so as to reduce the canal to a minute tube. The epithelial wall formed by this fusion on the dorsal side of the canal is gradually...
Page 680 - ... knob springing from the intermediate cell-mass opposite the fifth proto-vertebra. This knob is the rudiment of the abdominal opening of the segmental duct, and from it there grows backwards to the level of the anus a solid column of cells, which constitutes the rudiment of the segmental duct itself.
Page 110 - ... the animal pole is completely divided into small segments, which form a disc, homologous to the blastoderm of meroblastic ova; while the vegetative pole, which subsequently forms a large yolk-sac, is divided by a few vertical furrows, four of which nearly meet at the pole opposite the blastoderm.
Page 337 - Soi.,' vol. 1875. from the Protozoa, it is nevertheless worth while reviewing some of the processes by which this can be conceived to have occurred. On purely a priori grounds there is in my opinion more to be said for invagination than for any other view. On this view we may suppose that the colony of Protozoa in the course of conversion into Metazoa had the form of a blastosphere ; and that at one pole of this a depression appeared. The cells lining this depression we may suppose to have been amoeboid,...