A Treatise on Comparative Embryology, Volume 2Macmillan, 1881 |
Autres éditions - Tout afficher
A Treatise on Comparative Embryology: Vertebrata Francis Maitland Balfour Affichage du livre entier - 1885 |
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 |
Expressions et termes fréquents
adult alimentary tract allantois amnion Amniota Amphibia Amphioxus aorta appears artery atrophy auditory blastoderm blastopore body cavity brain branchial cardinal veins cartilage cartilaginous cells Chordata chorion cleft connected continuous derived differentiation diverticulum dorsal Elasmobranchii embryo epiblast epidermis epithelial epithelium excretory organs 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 outgrowths ovum peritoneal placenta posterior primitive streak probably pronephros region rudiment sack segmental duct segmental tubes shew shewn side somites splanchnic stage structure surface tail Teleostei thickened tissue TRANSVERSE trunk types vascular vein ventral ventricle vertebral Vertebrata vide visceral wall Wolffian duct yolk yolk-sack
Fréquemment cités
Page 502 - In other words, the primitive skeleton of both the fins consists of a longitudinal bar running along the base of the fin, and giving ofF at right angles series of rays which pass into the fin.
Page 318 - ... 4. Pilidium is the larval form which most nearly reproduces the characters of the larval prototype in the course of its conversion into a bilateral form. 5. The Trochosphere is a completely differentiated bilateral form, in which an anus has become developed. The...
Page 594 - Mullerian duct may be traced in this condition for a considerable number of sections, the peculiar features above described becoming more and more marked as its termination is approached. It continues to dilate and attains a maximum size in the section or so before it disappears. A lumen may be observed in it up to its very end, but is usually irregular in outline and frequently traversed by strands of protoplasm. The Mullerian duct finally terminates quite suddenly (Plate II, series i, No.
Page 287 - ... establishment of the two following propositions : — (1) That with the differentiation of the mesoblast as a distinct layer by the process already explained, the two primary layers lost for the most part the capacity they primitively possessed of giving rise to muscular and connective-tissue differentiations. (2) That the mesoblast throughout the triploblastic Metazoa, in so far as these forms have sprung from a common triploblastic ancestor, is an homologous structure. The second proposition...
Page 568 - 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. This section becomes very conspicuous in stained preparations by the intensity with which the nuclei of its walls absorb the colouring matter. The segmental organs of Peripatus, though formed on a type of their...
Page 108 - It forms the post-anal gut, and gradually narrows and finally atrophies. At its front border, on the ventral side, there may be seen a slight ventrally directed diverticulum of the alimentary tract, which first becomes visible at a somewhat earlier stage ifig.
Page 617 - Urochata and Moniligaster just the opposite condition obtains. But Balfour (1885), as most students after him concluded that one pair of nephridia to a segment is primitive, and that " in the generative segments of the Oligochaeta the excretory organs had at first both an excretory and a generative function, and that, as a secondary result of this double function, each of them has become split into two parts, a generative and an excretory.
Page 568 - ... 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 bodycavity.
Page 296 - ... caused by food-yolk. If, therefore, the mesoblast has been derived from the hypoblast, many more changes might be expected to have been introduced into its early development than if it had been derived from the epiblast. At the same time the hypoblastic origin of the mesoblast would assist in explaining how it has come about that the development of the nervous system is almost always much less modified than that of the mesoblast, and that the nervous system is not, as might, on the grounds of...
Page 549 - In Elasmobranch Fishes we thus have (1) a series of paired bodies derived from the sympathetic ganglia, and ("2) an unpaired body of mesoblastic origin. In the Amniota these two bodies unite to form the compound suprarenal bodies, the two constituents of which remain, however, distinct in their development. The mesoblastic constituent appears to form the cortical part of the adult suprarenal body, and the nervous constituent the medullary part.