68 



CELL-DIVISION 



general groups, as follows: (i) asymmetrical mitoses, in which the 

 chromosomes are unequally distributed to the daughter-cells, and (2) 

 multipoint- mitoses, in which the number of centrosomes is more than 

 two, and more than one spindle is formed. Under the first group 

 are included not only the cases of unequal distribution of the daugh- 

 ter-chromosomes, but also those in which chromosomes fail to be 

 drawn into the equatorial plate and hence are lost in the cytoplasm. 



Klebs first pointed out the occurrence of asymmetrical mitoses in 

 carcinoma cells, where Hiey have been carefully studied by Hanse- 



Fig. 32. Pathological mitoses in human cancer-cells. [GALEOTTi.] 



A. Asymmetrical mitosis with unequal centrosomes. B. Later stage, showing unequal dis- 

 tribution of the chromosomes. C. Quadripolar mitosis. D. Tripolar mitosis. R. Later stage. 

 F. Tri-nucleate cell resulting. 



mann and Galeotti. The inequality is here often extremely marked, 

 so that one of the daughter-cells may receive more than twice as 

 much chromatin as the other (Fig. 32). Hansemann, whose conclu- 

 sions are accepted by Galeotti, believes that this asymmetry of mito- 

 sis gives an explanation of the familiar fact that in cancer-cells many 

 of the nuclei are especially rich in chromatin (hyper-chromatic cells), 

 while others are abnormally poor (hypochromatic cells). Lustig and 

 Galeotti ('93) showed that the unequal distribution of chromatin is 

 correlated with and probably caused by a corresponding inequality 

 in the centrosomes which causes an asymmetrical development of the 

 amphiaster. A very interesting discovery made by Galeotti ('93) is 



