STAIN ACTS ON THE GRANULES 235 



undergo curious one-sided mitoses in some instances 

 (figs. 72, 73). 



We now investigated the "augmenting" action of 

 the extract of haemal gland. This was even more 

 powerful than that of atropine. So great was it that 

 one can employ a jelly which only contains three units 

 of polychrome stain which will never induce divisions 

 by itself; and if 3 cc. of the 100-per-cent extract of 

 dead haemal gland is also contained in the jelly, complete 

 divisions can be induced in lymphocytes without the 

 cells actually being coloured by the stain at all. Yet 

 all attempts at this stage to cause the extract to induce 

 divisions by itself had failed. 



Thus, by means of a mixture of a little stain, say , (\ 

 4 units, . 7 cc. of a 1-per-cent solution of atropine 

 sulphate, 3 cc. of the 100-per-cent extract of haemal 

 gland, 6 units of alkali solution, and 0.3 cc. of water 

 added to 5 cc. of coefficient jelly to make a total of 

 10 cc., one can induce advanced divisions in lympho- 

 cytes, without the cells staining at all in ten minutes. 



We have already stated that mitosis occurs about 

 the time when the stain has diffused into the cells 

 sufficiently to stain the granules. But now with the 

 combination of stain and the augmenting substances 

 mitosis will occur without the stain colouring the 

 granules at all. In spite of this, however, stain is 

 essential. Hence we suggest the theory that the 

 stain induces divisions by acting on the chromosome 



