OF THE CELL THEORY 189 



histogenic plasma should be exactly half the 

 nucleus. Thirdly, it cannot be overlooked that 

 the modes of formation of the first and of the 

 second polar bodies are precisely similar to each 

 other, and also that they agree precisely with 

 the changes that occur in the nucleus of an 

 ordinary epithelial cell during indirect division, 

 similarities which become very difficult to under- 

 stand if, as Weismann supposes, the two polar 

 bodies are of totally different nature, and do not 

 correspond to the halves of the nucleus of a 

 dividing epithelial cell. Lastly, it may be noted 

 that cases have been described in which more than 

 two polar bodies have been extruded. 



On the whole therefore, while acknowledging 

 the extreme ingenuity of Weismann's theory and 

 the service which its publication has rendered 

 by stimulating investigation and discussion, it 

 cannot be said that the theory is in accordance 

 with all the facts it seeks to explain, or that it 

 helps us very materially towards an understanding 

 of these facts. So far direct observation has 

 failed to show any difference in structure or in 

 mode of formation of the two polar bodies, or any 

 important respects in which their development 

 differs from the phenomena of ordinary mitosis. 

 These processes are so complicated and require 

 such extraordinary care and patience for their 

 successful investigation, that it is but natural to 

 assume that they have some deep and far-reaching 

 significance ; and it is well therefore to remember 

 that they are in no way specially concerned with 



