560 SUMMARY OF CURRENT RESEARCHES RELATING TO 



explicable why the black should dominate when crossed with the ticked 

 grey coat of the roof rat. If, on the other hand, the (black) rat has 

 arisen by the black colour spreading over and obscuring the ticking 

 beneath, then we could understand how it dominates in the first 

 generation ; also why the result is different from that when the black 

 variety of the Norway rat (Mus decumanus) is crossed with a grey rat. 

 It remains for further work to settle this point." 



Function of Corpus luteum.* — P. Bouin and P. Ancel have experi- 

 mented with rabbits, and have reached the following conclusions as to 

 the influence of the corpus luteum oo the uterus and the mammary 

 gland. The corpus luteum determines the phenomena of hyperhseniia, 

 hypertrophy, and structural transformation that are observed normally 

 in the uterus during the first part of gestation. It also conditions the 

 cellular multiplications which induce the development of the mammary 

 gland during this period. 



Regulation Phenomena. f — Al. Gurwitsch subjected to strong 

 " centrifugal force " the eggs of Strongylocentrotus lividus, Echinus 

 microtubercidatus, Rana, and Triton, and found that the plasmic struc- 

 ture was thereby dislocated. This is the first point of interest. 



The nucleus remained unaffected, however, and the maltreated ova 

 reconstituted their intricate plasmic structure and segmented. This is 

 the second point of interest. 



When frogs' eggs were subjected to the centrifugal machine, three 

 zones appeared, — (1) at the "animal pole" a thin-walled vesicle ; (2) a 

 zone of plasma, free from yolk ; (3) large yolk-masses at the "vegetative 

 pole." Yet these ova developed into well-formed blastula?. This illus- 

 trates what regulation means. 



Strongly rotated eggs of the newt segmented before there was any 

 restitution of the normal plasma-structure. 



Ovary of Anthropoids.} — H. Joseph has studied the ovary of an 

 orang and of a gibbon. He discusses the morphological nature of the 

 liquor folliculi, in which he finds definite cellular elements, and his con- 

 clusion is that the granulosa-cells give rise to both corpuscles and fluid. 



He also discusses the zona pellucida which his researches refer to a 

 follicular origin. The Call-Exner corpuscles, which seem to have an 

 intercellular origin in the zona, are discussed at length. Like Regaud 

 and Dubreuil, the author regards the granulosa cells as capable of pro- 

 ducing (1) the zona and Call-Exner, (2) the liquor folliculi and (3) the 

 intercellular substance. 



Development of Tatusia.§ — Miguel Fernandez has studied the 

 development of the Edentate known asMulita (Tatusialiybrida Desni.). 

 He finds that there is an inversion of the germinal layers, as in Mus 

 and Cavia, and that all the embryos of a birth (8-12) are developed 



* C.R. Soc. Biol. Paris, lxvi. (1909) pp. 689-90. 



t Trav. Soc. Imp. Nat. St. Petersbourg, xxxvii. (1908) pp. 139-89 (9 rigs.). See 

 also Zool. Zentralbl., xvi (1909) p. 270. 



X Arbeit. Zool. Inst. Univ. Wien, xviii. (1909) pp. 83-112 (1 pi. and 7 figs.). 

 § Morpbol. Jabrb., xxxix. (1909) pp. 302-33 (3 pis. and 3 figs.). 



