CKEATINE AUD CREATINIXE. 207 



starving animals. Thudichum mentions the fact that they 

 are particularly abundant in the muscles of wild animals, 

 and that the proportion diminishes in the same animals dur- 

 ing captivity. He cites the instance of a fox that had been 

 fed on meat for two hundred days at the Anatomical Insti- 

 tution in Giessen, in which the proportion of creatine was 

 not one-tenth part that contained in the flesh of foxes caught 

 by hunting. 1 It has likewise been found that the propor- 

 tion of creatine is very small in fat meat. 



It has been assumed by many authors that inasmuch as 

 the muscular tissue of the heart is in almost constant action, 

 it should contain more creatine than any other portion of 

 the muscular system; 2 but the late observations on this 

 point by Hofrnann, Halenke, and Yoit, show that the re- 

 verse of this is the case. These physiologists compared the 

 proportion of creatine in the heart and in the muscles of 

 the extremities, in oxen and in the human subject, and al- 

 ways found the quantity much less in the heart ; 3 still the 

 proportion of creatine has been found to be greater in tetan- 

 ized muscles than in the muscular tissue after repose. 



From the meagreness of our facts with regard to the phys- 

 iological relations of creatine and creatinine, it is evident 

 that there is much to be learned before we can understand 

 the process of its formation in the healthy organism and the 

 probable results of its retention or deficient elimination in 

 disease. At present we can only say that these principles 

 are probably produced in greatest part in the muscular tis- 

 sue. The fact that creatine has lately been demonstrated in 

 the brain would lead to the supposition that it is also one of 

 the products of disassimilation of the nervous substance. 



The average daily excretion of creatine and creatinine is 

 estimated by Thudichum at about 11-5 grains. Of this he 



1 Op. tit., p. 120. 



2 THUDICHUM, loc. cit. 



ROBIX ET YERDEIL, Traite de chimie anatomique, Paris, 1853, tome ii., 



p. 481. 



3 YOIT, loc. tit., p. 84. 



