MITOSIS DUE TO THE DYE 227 



prepared which contained each of them in turn, and 

 jellies were prepared which contained only the salts 

 sodium citrate and sodium chloride. Many experi- 

 ments \vere made from each, and several different 

 strengths of the different substances were tried re- 

 peatedly on fresh lymphocytes. It was thus ascertained 

 that Unna 's polychrome methylene blue (Grubler) con- 

 tains some substance which will induce divisions in 

 lymphocytes. It requires a high concentration of this 

 stain for this purpose, and this was the reason why 

 advanced divisions had not been seen in the several 

 years' previous work with this dye. Unless the jelly 

 contained Unna's stain, no mitosis whatever would 

 occur. Repeatedly they were tried, but none of the 

 other ingredients by themselves could be made at that 

 time to cause lymphocytes to reproduce themselves. 

 The 100-per-cent extract of hsemal gland by itself 

 certainly did not do so, nor did the atropine; but 

 both the extract and atropine and this was an im- 

 portant point greatly augmented the action of the 

 stain in inducing mitosis. By itself at least 10 units 

 (1 cc.) of polychrome stain were required to induce 

 mitosis; but if a certain quantity of atropine or of 

 extract, or, better still, of both, was also added to the 

 jelly, one could cause advanced mitosis in lymphocytes 

 with only two or three units of stain. It was a 

 remarkable state of affairs that neither atropine nor 

 extract would induce divisions by themselves, but that 

 they augmented the action of the stain in doing so to 

 a very marked degree. 



During all this experimentation, which occupied a 



