316 THE CAUSE OF HEALING 



There were two ways in which we might attempt to 

 isolate this active principle from the extracts. We 

 might analyse them and try the different substances one 

 by one. These analyses had, however, often been done 

 before, and it was considered better, in the first instance, 

 to try the well-known constituents of these extracts to 

 see if they would induce cell-division before we under- 

 took to analyse the extracts ourselves. 



We need not detail the vicissitudes of this research, 

 which occupied a long time. The constituents of the 

 extracts of the body are well known. It may be 

 remembered that the active principle in the extracts is 

 evidently thermostable, and remains in solution after 

 most of the proteins have been precipitated by heat. 

 We tried certain salts, and other substances, and we 

 have also tried urea, and at last kreatin (C 4 H 9 N 3 O 2 ) 

 was found to be a substance which will induce divisions 

 in lymphocytes (fig. 106) and leucocytes (fig. 107). 

 Kreatinin (C 4 H 7 N 3 O) is not effective in the experi- 

 mental ten minutes; but xanthin (C 5 H 4 N 4 O 2 ) is if 

 its action is augmented by atropine. 



The following table gives the strengths of kreatin 

 and xanthin required to be contained in the 10 cc. of 

 jelly in order to induce divisions in lymphocytes in the 

 experimental ten minutes, no atropine being employed, 

 but the jellies contained 1 cc. (10 units) of alkali 

 solution. 



Kreatin. 



0.02 gramme . . . No mitosis seen. 



0.04 " ... Early mitosis. 



0.75 " Well-advanced divisions. 



