CREATINE. 



67 



and vice versa. Hence, also, alternate layers of these two substances 

 may be found in the same calculus, and the idea of the "oxalic 

 diathesis" must, moreover, be regarded as a fiction. 



5. Pneumic Add. 



Pneumic acid was discovered by Yerdeil in 1851. It exists in 

 the organized substance of the parenchyma of the lung, and at all 

 ages of life. It has the same relation to the lungs that creatine has 

 to muscle, being a result, probably, of their metamorphosis. It 

 decomposes the carbonates in the blood, and thus sets free their 

 carbonic acid, which accounts for its greater proportional amount 

 in arterial than in venous blood (p. 44). 



The pneumate of soda is also found in the lungs, and in the blood 

 in them ; but it subsequently disappears, not being found in any of 

 the secretions. 



Fig. 35. 



SECOND DIVISION.. 



Neutral Nitrogenized Immediate Principles. (4.) 

 1. Creatine. (CgH^O^) 



Creatine forms transparent and very brilliant crystals (Fig. 35), 

 and is found in muscular tissue (both the striated and the smooth 

 fibre), in the blood, and in the urine. Lean meat contains more than 

 fat meat, and the heart most of 

 all. It constitutes about .067 per 

 cent, of human muscle. (Schloss- 

 berger.) The flesh of fowls con- 

 tains the largest quantity; that 

 of fresh water fishes the smallest. 

 It is always in a liquid state, dis- 

 solved in water. 



Origin. Creatine in the mus- 

 cular tissue is a constituent of 

 the "muscular juice," hereafter to 

 be described ; but, from the readi- 

 ness with which it is decomposed 

 into creatinine and urea, there is 

 no reasonable doubt that it is 

 derived from the decomposition of the muscular tissue, and is de- 



