98 



CELL-DIVISION 



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

 included not only the cases of unequal distribution of the daughter- 

 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 they have been carefully studied by Hanse- 

 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. 46). Hansemann, whose conclu- 



Pig. 46. — Pathological mitoses in human cancer-cells. [Galeotti.] 

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

 bution of the chromosomes. C. Quadripolar mitosis. D. Tripolar mitosis. E. Later stage. 

 F. Trinucleate cell resulting. 



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 (hyperchromatic 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 

 that asymmetrical mitoses, exactly like those seen in carcinoma, may 

 be artificially produced in the epithelial cells of salamanders (Fig. 47) 

 by treatment with dilute solutions of various drugs (antipyrin, cocaine, 

 quinine). 



