FACTS SUMMARISED 243 



think that, from the appearance of the cells, they are 

 about to divide into more than two daughter cells by 

 some quite atypical arrangement of the chromosomes. 

 The point is a very important one, for asymmetrical 

 divisions are reported to be frequently seen in can- 

 cerous growths. 



We may now summarise the facts learnt from the 

 mitotic divisions induced in lymphocytes by the aniline 

 dye. (1) Lymphocytes will not divide in vitro unless 

 they absorb the chemical agent. (2) The rapidity of 

 the onset of division depends on the rapidity of the 

 diffusion of the agent. (3) The time occupied by the 

 act of division depends on the amount of the agent 

 absorbed and the time occupied in the diffusion of the 

 substance into the cell. (4) If the diffusion is slow 

 the cells divide with the somatic number of thirty- 

 two chromosomes; but if it is rapid the number is 

 reduced. (5) A "reduction division" means that a 

 cell is very prolific, owing to its absorption of a large 

 quantity of the chemical agent. (6) The rapidity of 

 the absorption of the agent depends on the coefficient 

 of diffusion of the cell, the concentration of the agent 

 in the surrounding fluids, and on the presence and 

 strength of the factors which increase or decrease the 

 diffusion of the substances. (7) Lastly, it depends on 

 the vitality of the cells themselves. In fact, the 

 division of lymphocytes on a microscope slide depends 

 entirely on the presence or absence of a chemical 

 agent, and, if it is present, on its strength and on its 

 diffusion into the cell. 



In our opinion, judging from the mitotic figures 



