PRESIDENTIAL ADDRESS. 



301 



guanidin from the muscle to the blood, or (2) a decreased taking up from the 

 blood. In either of these ways the concentration of guanidin in the blood 

 necessarj' to enable it to manifest its stimulating action on the central nervous 

 system might be brought about. These observations must be repeated as the 

 amount of muscle available for analysis was too small to give absolutely reliable 

 results as to the amount of guanidin. As is well known muscle takes amino acids 

 from the blood and stores them at a higher concentration. Folin has shown 

 that it also takes up creatin and urea, and Mrs. Cathcart has shown that it 

 even takes ammonia salts from the blood. 



2. Jaffe i' had shown that glycocyamin, guanidin acetic acid, is methylated 

 in the body and so converted to creatin. This was confirmed by Domer.i* But 

 neither of these succeeded in getting an increase in the creati'nin of the urine 

 after the injection of methyl-guanidin. As Riesser points out the toxicity of 

 this substance makes it difficult to get results in this way. 



Thompson, 1" however, got a distinct increase in the creatinin output in the 

 dog and in the creatin output in the duck after parenteral injection of guanidin 

 carbonate. 



Some recent unpublished work by Wishart carried out this summer in my 

 laboratory shows that after injecting guanidin into dogs and hens the creatin 

 content of the muscle is markedly increased. 



I give a tabular view of his results : 



Creatin per cent, in muscles before and after injection of r/uanidin sulphate. 



These observations seem to me to be of very great importance since they 

 indicate quite clearly that creatin may be formed from guanidin. 



This formation of creatin from guanidin may explain the failure to recover 

 all the base when it is injected even although it is a substance which resists 

 so strongly the action of oxidising agents. 



Pommerenig found that guanidin given in small quantities was completely 

 excreted as such in thirty-six hours, but that in large doses only 30 per cent, was 

 recovered. 



Burns (loc. cit.) after the intra-muscular injection of 0-64 grm. of guanidin 

 hydrochloride, recovered in the next seventeen hours only about 25 per cent., 

 more than half of which had become methylated. 



That the whole process of the formation of creatin is carried on in the 

 muscles and that the liver has absolutely nothing to do with it may now be 

 considered as quite definitely settled. Experiments recorded by Mackie and 

 myself -" on the effects of exclusion of the liver from the circulation in geese and 

 ducks seem to be conclusive on this point, and they are confirmed by the result 

 of Towles and Voesctlin.^* 



Significance of Urinary Creatin. 



As Folin and others have clearly shown, the power of storing creatin in 

 muscle is very limited, and any excess in the food is apt to appear in the urine 

 either as creatin or possibly to some extent as creatinin. 



