24 EXCITORS OF CELL-DIVISION 



their number, can be clearly seen. In fact, a 

 lymphocyte in the act of division cannot be mis- 

 taken after a few have been recognised. 



Auxetics. In the first instance aniline dyes 

 were tried, and the following were found to be 

 capable of inducing the divisions. 



Artificial : azur II .... (0*5 c.c., 1 per cent) 1 



polychrome methylene blue . (0*8 c.c.) 



azur I .... (0'5 c.c. ,, ) 



methylene blue . ( ) 



All these dyes stain the granules of the cells 

 m vitro, and mitosis occurs at about the time 

 when the granules are colouring. The continued 

 diffusion of the dyes causes death. 



Some more dyes were then tried, but none were 

 capable of inducing divisions by themselves. 

 They were therefore tried with atropine. It has 

 already been stated that atropine sulphate is a 

 powerful kinetic, and although it is not itself 

 an auxetic, it greatly increases the action of the 

 substances which induce cell-division. This aug- 

 mentation, as it has been called, will increase the 

 action of the auxetic as much as fivefold; that 

 is to say, in order for a given substance to 

 induce divisions by itself, it is necessary for the 

 jelly to contain a certain quantity of it. If the 

 jelly contains less than this quantity, it is not 

 effective. Suppose now the jelly contains only 

 one-fifth of the effective quantity, but also con- 

 tains 0*7 c.c. of a 1-per-cent solution of atropine 

 sulphate, the divisions will occur as before. 



1 The numbers within parentheses refer to the strength of the 

 stock solution of the substance and the amount of it required to be 

 contained in the 10 c.c. of jelly. 



