1914] Editoriais 527 



may influence these relations, has been the basis for a large amount 

 Creatin content in of work in the attempt to solve the problem in- 

 muscie volving the relation between the Creatinin of the 



urine and the creatin of the muscle. The Creatinin of the urine is 

 excreted by any given individual in constant daily amounts, under 

 the same conditions of muscular development and tonus. Creatin 

 is a constant constituent of vetebrate muscle, which appears in the 

 urine, on a creatin- free diet, only as a result of (or associated with) 

 loss of tissue protein or failure to utiHze carbohydrate. 



The relative constancy of the creatin content in muscle has re- 

 cently been verified,^ the conception of species-specificity of the 

 creatin content supported, and the direct inter-relation between the 

 creatin of muscle and the Creatinin of the urine suggested on the basis 

 of the uniform and constant amount of creatin in muscle. A fur- 

 ther corroboration of the idea that the urinary creatin comes from 

 muscle creatin, and that the Creatinin of the urine has the same 

 origin, was based upon the analysis of fasting muscle and of the 

 determination of the creatin excreted in the urine under such cir- 

 cumstances. Data were presented which accounted in the urine, for 

 the greater part of the creatin lost from muscle. 



The absolute species-specificity of the creatin content in muscle 

 has recently been questioned,^ on the ground that the individual 

 variations of any one species are, in general, within the ränge of con- 

 centrations for the different species. While this Observation dimin- 

 ishes the force of the deductions on the constancy of the creatin con- 

 tent in muscle, it does not entirely invalidate the mass of evidence 

 which demonstrates this factor to be fairly uniform and character- 

 istic. The Solution of the problem will come with the accumulation 

 of more data both with the old and the new,^ perhaps with more 

 accurate, methods for the determination of creatin in muscle. At- 

 tention must be given, in interpreting these data, to the State of 

 health and the nutritive condition of the individuals used in such 

 studies. The experiments recently reported by Fohn^ show at least 



1 Myers and Fine : Jour. Biol. Chem., 1914, xiv, p. 9. 



2 Folin : Jour. Biol. Chem., 1914, xvii, p. 483. 



3 Baumann : Jour. Biol. Chem., 1914, xvii, p. 15 ; Folin, Ibid., 1914, xvii, p 

 475- 



* Folin : Jour. Biol. Chem., 1914, xvii, p. 493. 



