DETAILS OF MITOSIS 



99 



Normal multipolar mitoses, though rare, sometimes occur, as in the 

 division of the pollen-mother-cells and the endosperm-cells of flower- 

 ing plants (Strasburger) ; but such mitotic figures arise through the 

 union of two or more bipolar amphiasters in a syncytium and are 

 due to a rapid succession of the nuclear divisions unaccompanied by 

 fission of the cell-substance. These are not to be confounded with 

 pathological mitoses arising by premature or abnormal division of the 

 centrosome. If one centrosome divide, while the other does not, 

 triasters are produced, from which may arise three cells or a tri- 

 nucleated cell. If both centrosomes divide, tetrasters or polyasters 

 are formed. Here again the same result has been artificially attained 

 by chemical stimulus {cf. Schottlander, '^S). Multipolar mitoses are 



^ B 



Fig. 47. — Pathological mitoses in epidermal cells of salamander caused by poisons. 

 [Galeotti.] 



A. Asymmetrical mitosis after treatment with 0.05 % antipyrin solution. B. Tripolar mitosis 

 after treatment with 0.5% potassic iodide solution. 



also common in regenerating tissues after irritative stimulus (Strobe); 

 but it is uncertain whether such mitoses lead to the formation of 

 normal tissue.^ 



The frequency of abnormal mitoses in pathological growths is a 

 most suggestive fact, but it is still wholly undetermined whether the 

 abnormal mode of cell-division is the cause of the disea.se or the 

 reverse. The latter seems the more probable alternative, since nor- 

 mal mitosis is certainly the rule in abnormal growths ; and Galeotti's 

 experiments suggest that the pathological mitoses in such growths 

 may be caused by the presence of deleterious chemical products in 

 the diseased tissue, and perhaps point the way to their medical 

 treatment. 



1 The remarkable polyasters formed in polyspermia fertilization of the egg are de- 

 scribed at page 198. 



