514 SUMMARY OF CUERENT RESEARCHES RELATING TO 



Hatching of Axolotl's Egg.* — P. Wintrebert finds that this results 

 from a mechanical rupture of the envelope, which has become more and 

 more swollen by the progressive increase of internal fluid. The external 

 capsule tears first, admitting of a hernia and the bursting of the median 

 and internal capsules. The movements of the larvte help, but the burst- 

 ing occurs in the same way when the larvae are anaesthetized. 



Corpus luteum and Polyovular Follicles in Dasyurus.f — Chas. H. 

 O'Donoghue finds that the corpus luteum in the non-pregnant Dasyurus 

 viverrinus is derived from two sources. 1. Its characteristic lutein cells 

 are derived from the cells of the membrana granulosa hj hypertrophy 

 unaccompanied by direct or indirect cell-division. 2. The connective- 

 tissue network is derived from the ingrowths of the theca folliculi which, 

 in the ripe follicle, is not differentiated into tlieca interna and externa, 

 and these thecal ingrowths are accompanied by small blood-vessels. At 

 no stage is it possible to distinguish between the corpus luteum of the 

 non-pregnant female, i.e. corpus luteum spurium, and that of the 

 pregnant female, i.e. corpus luteum verum. 



Two cases of polyovular follicle are described in the Dasyure, 

 apparently the first record of the kind for Marsupials. On the whole 

 the evidence appears to be in favour of the view that polyovular follicles 

 result from the inclusion of two or more ova in one follicle. 



Polyembryonic Development in Armadillo. J — J. Thomas Patterson 

 has studied a practically unbroken series of early stages in the develop- 

 ment of Tatu novemrinchnn. It seems clear that the four emljryos are 

 the product of one ovum, and arise by precocious budding on the part of 

 the embryonic vesicle, rather than by a separation of blastomeres. It is 

 suggested that a rich supply of nutriment may be causally connected 

 with the phenomena of polyembryony. 



Interstitial Testicular Cells in Man. — Hans von Winiwarter finds 

 that the interstitial cells are not fixed unchanging elements ; they ex- 

 hibit fluctuations corresponding to the development and retrogression of 

 the seminiferous tulmles. The interstitial testicular tissue presents in 

 its history close analogies with that of the ovary. In both cases the 

 development is markedly cyclic. 



Mammalian Development. ||— Ed. van Beneden left behind him a 

 very important memoir on the early stages of development in the rabbit 

 and in the bat. It has been edited by A. Brachet. The fundamental 

 idea is tliat the " didermic " embryo of Mammals is comparable to a 

 blastula, not to a gastrula ; its external and internal envelopes are not 

 germinal layers in the strict morphological sense. The internal one is 

 but a simple envelope for the fluid of the blastodermic cavity, and is 



* C.B. Soc. Biol. Paris, Ixxii. (1912) pp. 799-802. 



t Anat. Anzeig., xli. (1912) pp. 353-68 (2 pis.). 



X Anat. Anzeig.. xli. (1912) pp. 369-81 (10 figs.). 



§ Anat. Anzeig., xli. (1912) pp. 309-20 (2 pis.). 



II Arch. Biol., xxvii. (1912) pp. 193-401 (14 pis. and 5 figs.). 



