430 BULLETIN OF THE 



ner as the first. After the escape of the [second] polar globule, that 

 which remains of the star approaches again the centre of the vitellus, 

 and becomes rounded in the form of a nucleus. The nucleus not only 

 disappears before each segmentation, but it twice becomes fused with 

 the surrounding protoplasm and twice individualized before the first 

 segmentation. 



In this description that which least coincides with the ideas I have 

 formed from my own observations and those of others is the statement 

 made in the last sentence, together with that which makes the nucleus 

 (germinative vesicle) disappear, and again appear before the formation 

 of the polar globule. Although recognizing the spindle fibres as stouter 

 than the remaining rays, Fol does not admit any fundamental difference 

 between the two. The equatorial thickenings were not seen, and the 

 lateral zones only in the formed polar globule. I have elsewhere stated 

 my reasons for inferring that the changes succeeding the formation of 

 the first polar globule are more complicated than has hitherto been 

 assumed by Fol or any other observer. 



I wish to call attention to only one or two points in his critical 

 review of other authors and in his " reflexions." Touching the role of 

 the nucleus, Fol says : ''It cannot serve as a centre of attraction pre- 

 siding over cellular division, since these centres of attraction arise at 

 the very limit of nucleus and protoplasm, and since the nucleus, if so 

 be that it is able to persist and divide, would undergo these successive 

 modifications only in a manner altogether passive, at least as passive 

 as the cell or the segmentation sphere in which it is situated." And 

 again, " // ne se divise pas, il est divise^ I believe there are very good 

 grounds for adopting this opinion. 



The fibres of Biitschli are filaments of sarcode, according to Fol, and 

 the grains (thickenings) are varicosities of the filaments, which have 

 nothing whatever to do with the nucleoli. This is the first paper, I be- 

 lieve, in which Fol admits that the nucleus does not appear to be dis- 

 solved. It changes in volume and appearance, and loses its contour, 

 he says, and its substance obeys the call of the centres of attraction, 

 which, so to speak, tear it in two. 



BtJTSCHLi (76, pp. 215-249, 380-394, Taf. I. -IV.) contributes val- 

 uable information on the features of maturation in eggs, of worms and 

 gasteropods, a part of which was made known in his preliminary account. 

 In Nephelis the youngest eggs studied exhibit near the somewhat flat- 

 tened pole the spindle-shaped body already described, lying with its axis 

 nearly in the axis of the egg. A broad equatorial zone of thickenings 



