234 RICHARD ASSHETON. 



and more granular and duller than the other two. This 

 description refers to two specimens of Vespertiliomurinus 

 examined in the fresh state. The same holds good for speci- 

 mens of Rhinolophus ferrum equinura. 



On the other hand, Duval^ who describes two specimens of 

 the same species Vesper tilio murinus and speaks from pre- 

 served and stained material studied in section, asserts that the 

 two larger spheres are the darker ones, *' deux plus petits et 

 plus clairs ; deux plus gros et plus fonces/^ 



According to Duval the two small clear spheres give rise to 

 the ectoderm. Van Beneden and Julin had unfortunately no 

 stages between the four-segment stage and the completed 

 blastodermic vesicle. It would seem, however, that they con- 

 sidered the large clear cells to be ectodermal, and the smaller 

 darker cells hypoblast. 



Again, there is a disagreement as to the position of the 

 inner mass on the wall of the blastodermic vesicle. Duval 

 concludes that the inner mass is attached to the base of the 

 cup formed by the enveloping outer layer, whereas van Beneden 

 and Julin find it at the mouth of the cup, which two accounts 

 are quite irreconcilable. In Duval's case it is Ve spertilio 

 murinus which is being described, and in van Beneden and 

 Julin^s it is Rhinolophus ferrum equinum. But the 

 difference is so great that I can hardly think it should be 

 accepted as a generic variation. It is impossible to derive 

 van Beneden and Julin's figs. 5 and 6 from Duval's fig. 24, or 

 vice versa. 



Van Beneden and Julin's account is derived from two living 

 specimens, and Duval's from one specimen which had been 

 subjected to the process of preservation and staining, and had 

 been made into sections. 



Duval unfortunately never shows the presence of zona 

 radiata in any figure, and I do not think that he ever makes 

 any mention of it. It is difficult to imagine such an embryo 

 existing in a uterus unless there is a zona present. Van 

 Beneden and Julin, however, show the zona in all their figures. 



One could have felt more confident that this specimen was 



