CHAPTER VI 



CREATIN AND CREATININ. OTHER URINARY BASES. 

 OXYPROTEIC ACIDS. UROCHROME. 



CREATIN AND CREATININ 



IN the current lecture two important end-products of 

 metabolism will first be carefully considered, creatin and 

 creatinin. The importance of these two closely related sub- 

 stances is at once apparent when we recall that a fully grown 

 human being excretes as an average about one gram of 

 creatinin in the urine in the course of twenty-four hours, and 

 that this substance, from a quantitative standpoint, is a 

 prominent member of the group of excretory products which 

 represent the nitrogen fraction escaping transformation 

 into urea. 



In attempting to present a precise statement of the 

 knowledge we possess as to the nature and importance of 

 these substances, the first impression obtained by tracing 

 the history of this metabolic problem is a very confusing and, 

 indeed, a depressing one. If, however, one works with de- 

 termination through the tangle of actual and seeming con- 

 tradiction which involves the subject, he will gradually 

 realize a pleasant satisfaction in learning that conditions are 

 not really as bad as they at first appear. The pioneer 

 work of the last ten years has basically cleared the ground, 

 and if to-day a survey be made free view in more than one 

 direction is found possible. 



Quantitative Estimation. In the development of the 

 creatin problem may be seen, as often is the case in physio- 

 logical chemistry, how actual progress first became appreci- 

 able after analytical chemistiy had provided an applicable 

 method of estimation with which the physiological investiga- 

 tor could work with satisfaction. In this instance we are 

 much indebted to 0. Folin 1 for his carefully elaborated 



1 0. Folin, Zeitachr. f. physiol. Chem., W, 223, 1904. 

 122 



