. Anatomischer Anzeiger. Anatomy, Comparative; Anatomy, Comparative. 517 low tliick process (Placental Process Fig. 3) of the luenibranes is sent in. The cells of the outer layer of the serous envelope on this pro- cess are i)cculiarly modified, being columnar and their nuclei are larger, irregular in shape, and stain deeper. Many large vacuoles are found in these cells. There can be no doubt that these cells ab- sorl) albuminous particles from the white. It seems to me that we have here in a very primitive condition the structure described by DiTVAL as the placenta in Birds. 16. In hatching,
. Anatomischer Anzeiger. Anatomy, Comparative; Anatomy, Comparative. 517 low tliick process (Placental Process Fig. 3) of the luenibranes is sent in. The cells of the outer layer of the serous envelope on this pro- cess are i)cculiarly modified, being columnar and their nuclei are larger, irregular in shape, and stain deeper. Many large vacuoles are found in these cells. There can be no doubt that these cells ab- sorl) albuminous particles from the white. It seems to me that we have here in a very primitive condition the structure described by DiTVAL as the placenta in Birds. 16. In hatching, tlie yolk-sac passes into the interior of the body where it lies for several months, 2. Trionyx japonicus. 17. In Trionyx, when the allantoic vesicle spreading into the extra-embryonic coelomic cavity, assumes a flattened shape, it is as represented in Fig. 4. It corresponds to Fig. 2 of Clemmys. The main point of dif- erence lies in the fact that in Trio- nyx, the left lobe is and remains to the end, rudimen- tary. The allantoic vesicle, instead of going round the sero- amniotic connection, l)roducing the poste- rior constriction, as in Clemmys, pushes the connec- tion before it and makes it shift its position continually forward toward the anterior end of the egg. The result is that after a while, the seroamuiotic connection becomes the most anterior part of the amnion, the main body of the amnion assuming the shape of a bag hanging pendant by the sero-amniotic connection. The final shape and arrangement of the foetal membranes are represented in Fig. 5 and Diag. VII. 37. Seen. J^roKO-Zi 7Xa> Sirgus JPni'f/iipa, xj/^.. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Anatomische Gesellschaft. Jena : G. Fischer
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