THE MECHANISM OF DEVELOPMENT 151 



at one pole, some of them perhaps being lost altogether in the 

 mass of the cytoplasm. 



2. Multipolar mitosis, in which the number of centrosomes is 

 more than two and the resulting daughter cells three or more. 



Both these abnormal processes, however, are characteristic of 

 abnormal growths, such as cancers and tumors, and are therefore 

 considered as pathological. It is a suggestive fact that such 

 irregularities may be artificially produced by poisons and other 



D E F 



Fig. 23. Pathological mitoses in human cancer cells 



A, asymmetrical mitosis with unequal centrosomes ; B, later stage, showing unequal distri- 

 bution of the chromosomes ; C, quadri polar mitosis ; Z>, tri polar mitosis'; , later stage ; 

 f, trinucleate cell resulting. After Wilson, from Galeotti 



chemical substances such as chloral, quinin, nicotin, antipyrin, 

 cocain, etc. 1 (See Figs. 22 and 23.) 



3. Amitotic division? that is, division without the forma- 

 tion of the amphiaster or the splitting of the chromosomes. 

 This form of cell division is effected by constriction, resulting 

 simply in a lump division of the mass of the nucleus, without 

 reference to qualitative considerations. In this case the daughter 

 cells would not, presumably, be alike. This form of cell division 



1 Wilson, The Cell, pp. 97, 98. Ibid. p. 114. 



