284 SUMMARY OF CURRENT RESEARCHES RELATING TO 



tropkoblast layer, among the cells of which accumulation extravasated 

 maternal blood circulates. The Carnivora are perhaps intermediate, and 

 the sheep's placenta is at that end of the series of plicate forms which 

 closely approaches the cumulate type. The elephant's placenta at half 

 term and at full term closely approaches that of the sheep, but that of 

 Hyrax is typically cumulate. 



Ferments of the Placenta.* — Charrin and Goupil adduce some facts 

 which suggest that the placenta has a glandular function. It can re- 

 tain and modify various substances, or continue processes elsewhere 

 begun. There is evidence of a glycolytic substance (forming alcohol 

 from glucose) and also of a proteolytic fermentation. 



Amnion-Invagination in the Formation of Chick's Lens.f — Aurel 

 von Szilly notes that in many cases during the formation of the lens- 

 vesicle there is an invagination of a small portion of the amnion. The 

 same was also noticed in connection with the development of the 

 auditory vesicle. 



Pre-Oral Gut in Bird Embryos.! — Giunio Salvi has made a detailed 

 study in many birds of that part of the anterior gut which precedes the 

 formation of the stomodamm, and is known as the pre-oral gut. 



Double Embryo of Florida Alligator. § — Albert M. Reese describes 

 what is probably a unique case, the occurrence of two embryos in the 

 egg of the alligator. The egg was of the usual size ; the yolk was 

 single and of the usual size ; the two embryos were entirely distinct, 

 but lay so close together that their vascular areas were flattened against 

 each other. About 15 pairs of mesoblastic somites were visible, and the 

 neural canal was practically inclosed. 



Double Embryo of a Lizard.|| — J. J. Tur describes a double- 

 embryo in a Javanese lizard (Mabuia multifasciata), which apparently 

 arose from a common blastoderm with two gastrula-invaginations, 

 probably far separate though included in one area pellucida. 



Giant Tadpoles. *[ — Emil Yung describes some giant tadpoles of 

 Rana esaihnta, collected in August from a quiet shallow part of the 

 Aire, near Geneva. Not only were they unusually large, but the intes- 

 tine was unusually long in proportion to the body. While tadpoles 

 hatched artificially had an intestine 122 mm. in length (8 '62 times the 

 length of the body), the giant tadpoles had an intestine 2;-55*8 mm. in 

 length (12*71 times the length of the body). Similar figures are given 

 for different stages. The author thinks that the length of the intestine 

 is mainly related to the volume and weight of the nutritive contents of 

 the gut. The giant tadpoles had the intestine absolutely filled with the 

 rich mud of their habitat. 



* Comptes Eendus, cxlii. (1906) pp. 595-7. 

 t Anat. Anzeig., xxviii. (1906) pp. 231-4 (4 figs.). 



X Atti Soc. Toscana Sci. Nat. Pisa, xxi. (1905) pp. 83-158 (1 pi., 22 figs.). 

 § Anat. Anzeig., xxviii. (1906) pp. 229-31 (1 fig.). 



|| Arbeit. Zootom. Lab. Warscnau Univ., xxxiii. (1904) pp. 1-35 (1 pi. and 33 

 rigs.) (Russian.) See also Zool. Zentralbl., xiii. (1906) pp. 117-18. 

 1 Arch. Sci. Phys. Nat., xx. (1905) pp. 595-7. 



