[VOLUTION ABY BIOLOGY 



the- nucleus appears simply to constrict into two or more 

 rts (Fig. 36) . This is known as direct or amitotic nuclear division. 



It is frequently met with in 

 degenerating cells and patho- 

 logical tissues, but it is doubtful 

 if it ever occurs (in the higher 

 organisms at any rate) in cells 

 which are destined to undergo 

 bng - continued multiplication., 

 We may therefore regard-it as 

 a more or less abnormal proc 1 

 with which we have no ne 

 cern ourselves any further. The phenomena of mitosis, on 

 Her hand, are thorough y normal and practically universal, 

 ,3 wo shall see later on, they are of the deepest significance 

 the point of view of the theories of heredity and variation. 



;;G. Ainitotic imcleiu Division 

 as seen in Cells from the Cavity 

 of the Paraph ysis in Sphenodon, 

 X 1000, 



nil. nuclei. 



i 



