434 BULLETIN OF THE 



the disappearance of the dot, or at least a part of it ; bat in general one 

 must conclude from his own observations, as well as those of other ob- 

 servers (Strasburger, Flemming), that the nucleus, metamorphosed into 

 a spindle, is ejected from the yolk. From his own studies he finds no 

 occasion for assuming that this ejection is incomplete. Still, in view of 

 the positive evidence that in conifers a portion of the egg nucleus, as 

 shown by Strasburger, remains behind, he is compelled to admit that 

 he cannot with absolute certainty deny that a part of the nuclear plate 

 of the metamorphosed egg nucleus becomes detached during the elimi- 

 nation to form the basis of one or several of the little nuclei which after- 

 wards appear in the yolk. Two points in his own observations may 

 also be favorable to this view : the origin of the new nuclei in definite 

 spatial relation to the place where the nucleus is ejected, and the ap- 

 parent connection (in Nephelis) of the eliminated egg nucleus with some 

 of the newly formed nuclei by means of fine filaments. 



The signification of the polar globules as understood by Biitschli will 

 be further considered in connection with the subject of fecundation. 



KoROTNEFF (76, pp. 392-394, PI. XVI. Figs. 10-13) reports for 

 Lucernaria the existence of a micropyle, which is quite readily seen in 

 fresh eggs. He says it is placed in a depression. It appears as a round 

 clear spot (Fig. 12) when seen from above. The germinative vesicle at 

 the maturity of the egg moves from the interior to the surface. At the 

 same time it takes on an elliptical form and its peripheral extremity ap- 

 pears to become fused with the vitelline membrane. " It has appeared to 

 we," adds Korotneff, " that the micropyle is always formed at the place of 

 this union. ^^ 



From the latter part of this description, which I have taken the lib- 

 erty to italicize, I think it is nearly certain that the supposed micropyle 

 is the same as the " pellucid spot " seen by Whitman, — the corpuscle 

 in the central area of the superficial star of the archiamphiaster. It is 

 peculiar, and perhaps an objection to this view, that the surface of the 

 egg is at this point depressed rather than elevated, yet a like peculiar- 

 ity is to be observed in eggs of Ptero trachea. (0. Hertwig, '78", p. 208, 

 Taf. XI. Fig. 8.) However that may prove to be, I think this explana- 

 tion will not be found to contravene any of the further observations 

 made by Korotneff, who finds in freshly deposited eggs that a globule * 



* Korotneff erroneously holds this polar globule to be the expelled germinative 

 dot, just as Loven and others have long ago done. 



It is only a typographical error, which here (p. 393) makes Loven responsible for 

 the idea that the nucleus (instead of nucleolus) escapes as polar globule. 



