554 BULLETIN OF THE 



as the nuclear substance in the remaining portion of the egg. There 

 are some indications that its substance acts less vigorously than that of 

 the larger cell, but it certainly has not lost all its reconstructive ability. 

 It is therefore unlike any known products of secretion or defecation. 



Biitschli has advocated the opinion that the principal physiological 

 signification of the globules consists in the removal of a part of the 

 " Eikern " (germinative vesicle) ; and Strasburger adopts the same view 

 in saying that the nucleus frees itself of certain constituents, and thus 

 makes ready for the approaching fecundation. BUtschli's opinion that 

 this elimination is due to fecundation, or is at least a phase in the early 

 development of the egg, not in its maturation, must be abandoned, since 

 it has been shown that the globules are in many cases formed before 

 the approach of spermatozoa. It seems, however, to be indicative of a 

 mutual influence of spermatic and polar-globule substances, that the 

 male pronucleus is retarded in its migration and growth up to the time 

 of the detachment of the second globule, as though the presence of the 

 polar-globule substance acted as a hindrance to its normal development. 



Balfour has adopted nearly the same view as Biitschli. He explains 

 the act as consisting in the removal of parts of the germinative vesicle, 

 more or less essential to the further independent development of the 

 cell, to make room for the supply of the necessary parts to it again by 

 the spermatic nucleus. This hypothesis would serve, he thinks, to ex- 

 plain why it is that polar globules have not been found in those groups 

 (Arthropoda and Rotifera) where parthenogenesis is most frequently 

 encountered. The fact that parthenogenesis is possible where impreg- 

 nation is the normal occurrence, may appear, he says, to be an objec- 

 tion ; but it cannot be denied without further study that development 

 in such cases may be due to the suppression of the globules, and that 

 when they are formed development without impregnation is less 

 possible. 



An objection to this latter assumption is the tardiness in the events 

 of maturation which must be admitted when fecundation is under the 

 control of the parent. If there were a suppression of the polar globule 

 in the case of unimpregnated eggs of the honey-bee, for example, then 

 the first steps in the formation of the globule must normally take place 

 after the egg has passed the seminal receptacle, for the fecundation or 

 non-fecundation of any given egg is not previously determined. In 

 other words, the development of the egg up to that epoch must be the 

 same in all cases, whether a polar cell is to be formed or not. Such a 

 delay in the events of maturation may not be impossible, but does not 



