STUDY OF CELL MECHANICS 



479 



development will be apparent on the inspection of the figures. 

 Boveri along with a number of other investigators has pointed 

 out that there is a constant relation between the size of the aster 

 and the protoplasm it controls. That is, a monaster would be 

 larger than a single aster of an amphiaster were the egg the 

 same size in both cases. These spindles with a monaster history 

 form an exception to this rule. Again we are confronted with 

 two possible explanations. If we adhere to the old view of a 

 definite archoplasmic substance, then we can say that while 



Fig. K 



the centrioles may have failed to divide, this substance has 

 increased in amount. Hence at the second division cycle, the 

 asters are larger. The more likely explanation, however, 

 seems to me to be in the relative amounts of chromatin, in 

 these eggs. A number of investigators have maintained that 

 the increase in the size of the asters is due, in part at least, 

 to the absorption of nuclear sap, which is set free in the egg 

 cytoplasm when the nuclear wall disappears. In these eggs 

 with larger asters, we have just double the number of chro- 

 mosomes that are found in the first spindle. If the nucleus 

 contributes to the growth of the aster, the large size of the asters 

 in eggs with a monaster history is not difficult to explain. 



