igii] Isidor Greenwald 87 



the other is by no means as readily accomplished as had been 

 assumed. Polin and others have found that the ingestion of creatin 

 does not increase the Creatinin of the urine. If given in doses that 

 are not extremely large, especially when the subject is on a low 

 protein diet, all the nitrogen of the creatin may be retained. With 

 larger amounts, or in conjunction with a high protein diet, creatin 

 appears in the urine. 



Muscular work, if the food be sufficient, is quite without effect 

 upon the Creatinin excretion. The work of van Hoogenhuyze and 

 Verploegh^ and Shaffer^'^ is quite conclusive in this regard. Brown 

 and Cathcart/^ however, have found that while the total amount 

 of Creatinin in isolated frog muscle was increased by work, in 

 mammalian muscle, with circulation intact, it was decreased. 

 Considerable doubt has been thrown upon their results by Pekel- 

 haring and van Hoogenhuyze,^^ who found that work did not 

 affect the creatin and Creatinin contents of frog muscle. 



Although not influenced by the amount of work done, the 

 Creatinin excretion bears a direct relation to the general State of 

 the muscular tissues. Conditions that affect ability of the muscles 

 to do work are characterized by a low Creatinin excretion and some- 

 times by the appearance of creatin in the urine. 



The interesting work of Pekelharing and van Hoogenhuyze 

 should be mentioned in this connection. These observers found 

 that, although the tetanizing of muscle did not increase the creatin 

 content, conditions which increased the tone of the muscle were 

 characterized by a high content of creatin. They are of the opinion 

 that creatin is the product of a specific tone-metabolism, which is 

 very different from the ordinary contraction metabolism. Lingle,^^ 

 from histological studies upon smooth muscles, has come to a con- 

 trary conclusion. He believes that tone is a condition of partial 

 contraction. 



' Van Hoogenhuyze and Verploegh : Zeitschrift für physiologische Chemie, 

 1908, Ivi, p. 415. 



"Shaffer: American Journal of Physiology, 1908, xxii, p. 445. 



" Brown and Cathcart : Biochemical Journal, 1909, iv, p. 420. 



" Pekelharing and Van Hoogenhuyze : Zeitschrift für physiologische Chemie, 

 1910, Ixiv, p. 262. 



" Lingle : American Journal of Physiology, 1910, xxvi, p. 361. 



