300 SUMMARY OF CURRENT RESEARCHES RELATING TO 



general anomalies in the development of kidney and ureter are more 

 easily explicable on the old theory of Kolliker that the kidney arises 

 from the ureter, than on the current view that it arises independently 

 of the ureter from the middle layer. In the latter case it is difficult to 

 understand why the absence of one kidney should be so frequently asso- 

 ciated with the absence of the corresponding ureter, or why triple kidney 

 should be associated with triple ureter. 



Abnormalities in Development of Chick.* — Dr. Ch. Fere notices 

 that not a few authors have described cases where the area opaca in the 

 chick has developed normally in the absence of the embryo, showing 

 that a certain independence of growth of area opaca and area pellucida 

 must exist. Again, in the area opaca the vascular and the non-vascular 

 zones are not intimately related, for the one may develope independently 

 of the other. The author describes an interesting case observed by 

 himself in which the non-vascular zone of the area opaca was very 

 slightly developed, so that the blastoderm consisted of a somewhat 

 abnormal embryo surrounded by a vascular area resting almost directly 

 on the yolk. This condition may be described as the complement ot 

 the much commoner case where the non-vascular zone developes at the 

 expense of the embryo. 



Chick's Amnion-Allantois.j — Dr. C. Creighton describes a peculiar 

 system of lymphatic sheaths around certain tributary branches and 

 capillary loops of the umbilical vein on the inner lamina of the chick's 

 allantois, where it is adherent to or fused with the amnion. He brings 

 forward evidence to show that the " lymph " required in the later period 

 of incubation for the absorption of yolk is obtained from the liquor 

 amnii, partly by direct transudation from the amnion-sac, where it 

 presses upon the proximal pole of the yolk-sac, partly by that system of 

 lymphatic sheaths of the allantoic vessels, filled with lymph from the 

 adherent amnion, to which yolk is brought from the yolk-sac by a round- 

 about way, along with much of the albumen from the albumen-sac. 



Development of Crocodile.^ — Dr. A. Voeltzkow has studied Croco- 

 dilus madaga8cariensis Grand, in its native haunts, and has succeeded in 

 obtaining an abundant supply of eggs. The eggs are laid in nests in 

 dry sandy banks, the nest being often a hole 1/3-1/2 metre deep, which 

 is afterwards carefully filled up by the mother. The egg-laying occurs 

 at night, and during the period of development (2^-3 months) the nest 

 is regularly visited by the mother. The author succeeded in demon- 

 strating the truth of the statement that the young, just before hatching, 

 produce a loud call-note, to which the mother responds by opening the 

 nest. He further found that in the case of eggs kept in boxes of sand 

 in his house, a heavy step or a vibration in the vicinity of the box re- 

 sulted in the production of the call-note. There can be little doubt 

 that the movements of the mother in the vicinity of the nest produce 

 vibrations in the loose sand, which induce the imprisoned young to pro- 

 duce the call-note. After liberation the young accompany the mother 

 to the water. 



* Journ. Anat. Physiol., xxxvi. (1900) pp. 99-102 (1 pi-)- 



t Journ. Anat. Physiol. Norm. Path., xxxiii. (1899) pp. 527-44 (2 pis.). 



X Abh. Senckenberg. Naturf. Ges., xxvi. (1899) pp. 1-150 (17 pis. and 18 figs.). 



