MUSEUM OF COMPARATIVE ZOOLOGY. 563 



(Eufs genetiquement plus ages que des oeiifs qui, chez une autre, sont arrives 

 dans I'oviducte, et deja revetus d'albumen. II y a meme plus : des oeufs 

 venant d'etre pondus n'ont quelquefois pas atteint encore la phase de remis- 

 sion des globules polaires, alors que, chez d'autres Helices, ces corpuscules 

 s'observent deja dans des oeufs occupant le quatrieme ou cinquierae rang dans 

 le haut de I'oviducte." All the phenomena which we have hitherto studied 

 (i. e. up to the formation of the polar globules) may be observed, he says 

 (p. 375), "in the egg contained in the diverticulum" ; and a little farther on 

 he adds, that Figs. 15 and 18 have been furnished by an egg from the oviduct. 

 In view of the great variability thus described by him it certainly would 

 not be impossible that an egg taken, as this was, from the oviduct, should have 

 already produced the two polar globules. I have not the least doubt that that 

 is what has transpired in the present instance, and consequently that the 

 author has overlooked the existence of previously formed polar cells. If it 

 were permitted from his descriptions to suppose that Fig. 18 was not from the 

 same egg as Fig. 15, then the latter might possibly represent the first archi- 

 amphiaster, — a stage antecedent to the formation of ]3olar globules ; but in 

 his explanations of the plates (see also p. 372) he describes Fig. 18 as " ce qui 

 reste du corps radiaire de la figure 15, quand on a degage par de legers coups 

 sur la lamelle la majeure partie de la substance qui cache les noyaux." Still 

 the difterence in the relative sizes of the nucleolar bodies in the two figures 

 may possibly be taketi as evidence that they were not drawn from the same 

 egg, and that the author only intends in his " Explanations " to convey the idea 

 that Figs. 15 and 18 are drawn from eggs of the same degree of advancement. 

 However it may be with Fig. 15, Fig. 18 represents not the vesicular remnants 

 of two astral figures, but the two pronuclei already closely approximated. It 

 is more reasonable to suppose that Perez has in this case overlooked the exist- 

 ence of the polar globules (a thing which may very naturally happen, since 

 they are easily detached) than that all observers before him have overlooked 

 the presence of a large vesicular structure embracing the central portion of 

 each aster. He asserts that " such is the transparency of the two ' cellules,' 

 when sufficiently young, that, owing to the vitelline granulations which indi- 

 cate their shapes by enveloping them on all sides, one often divines them 

 rather than sees their contours." (p. 373.) I think it must be that they are 

 " divined " in all cases where the examination is made before the formation of 

 the polar globules. He says himself that they are much more easily shown 

 before than after that event (p. 381). 



He recognizes the existence of a spindle, but considers it of little impor- 

 tance. The equatorial enlargements of its fibres are not prominent, although 

 sufficiently evident in most cases. They consist of a gradual thickening of the 

 rays up to the equator, or of nodosities distributed along the rays at the middle 

 third of the spindle. They never appear under the form of a nuclear plate, 

 an organ, says Perez, to which is attached a great importance, since it is con- 

 sidered as destined to give rise to the nuclei which are subsequently seen at 

 the extremities of the spindle, and, when the latter has ceased to exist, in its 



