i2 4 SEGMENTATION [CH. vm 



multipolar spindles in dispermic eggs, some of which have 

 already been referred to and others will be mentioned later. 

 Among other things, they have figured largely in the dis- 

 cussion of HARTOG'S hypothesis of a dual force acting at 

 unlike poles as the cause of mitotic division. It is impossible 

 here to enter into HARTOG'S ingenious explanation of multi- 

 polar spindles on his hypothesis ; it must suffice to say that 

 he maintains that they are in no way inconsistent with it. 



