22 EXCITORS OF CELL-DIVISION 



the chemical agents, which, on being absorbed 

 by the cells, cause them to divide, or to become 

 excited, or to remain unaffected as the case may 

 be, according to the nature of the substance. In 

 the former publication experiments were described 

 which demonstrated the fact that the substances 

 which caused division of the cells in vitro on the 

 jelly film also caused the proliferation of healing 

 in vivo when directly applied to ulcers. In the 

 present paper, however, we shall only describe 

 the results obtained with the new substances -in 

 vitro with the jelly method ; the in-vivo experi- 

 mentation which must necessarily follow will be 

 described on a future occasion. 



The method has been fully described (1, 2), 

 and need not here be repeated in detail. It will 

 suffice to say that the jelly basis from which the 

 films on the slides are made is known as " co- 

 efficient jelly," and contains the necessary salts 

 to keep the cells alive ; it is prepared in such a 

 manner that other substances (e.g. auxetics or 

 kinetics) from stock solutions can be added to it 

 up to a total of 10 c.c. ; and when a certain 

 quantity of alkali (sodium bicarbonate) has also 

 been added the substance or substances to be 

 tested on the cells are absorbed by them, and 

 the result watched. 



In order to induce divisions (auxetic action) 

 it is necessary to keep the slides at blood heat; 

 and every slide is examined after ten minutes, 

 because it may be taken as a general rule that, 

 owing to the loss of vitality, unless the cells are 

 in the act of division at the end of ten minutes, 

 they will never divide under the experimental 



