72 THE SIMPLER NATURAL BASES 



After two months' gestation, 100 grm. of voluntary muscle of the 

 foetal calf contained 22 mg., after nine months 250*4 mg. Ac- 

 cording to Mellanby [1908] creatine is not present in chick's muscle 

 until the 1 2th day of incubation and the maximum content is only 

 reached after hatching. 



In the rabbit and in the fowl the percentage of muscle creatine 

 increases during starvation [Mendel and Rose, 191 1, 2], probably owing 

 to diminution of the non-creatine portion of the muscle. According 

 to Myers and Fine [1913] it increases in the earlier part of starvation 

 and afterwards diminishes. In malignant and some chronic diseases, 

 but not in acute disease, the creatine content of muscle is diminished 

 [Chisholm, 1912], apparently owing to diminished production. 



Letsche [1907] found creatine in the blood serum. 



Creatine is generally absent from mammalian urine, but it may be 

 present in various conditions. It completely replaces creatinine in 

 birds' urine [Paton, 1910] and occurs also normally in the urine of 

 infants [Funaro, 1908] and of children [Rose, 1911 ; this paper should 

 be consulted for further literature], [Folin and Denis, 1912], [Krause, 

 1913]. In women creatine occurs in the urine immediately after 

 menstruation, also during and after pregnancy [Krause, 1911 ; Krause 

 and Cramer, 1910]; its excretion is a concomitant of lactation 

 [Mellanby, 1913]. 



In man creatine appears in the urine when no carbohydrates are 

 taken as food, therefore in starvation [Cathcart, 1 907 ; Benedict and 

 Diefendorf, 1907; Mendel and Rose, 1911, 2] and also on a diet of 

 fats and proteins [Cathcart, 1909 ; Mendel and Rose, 1911,1]. Creatine 

 further appears in the urine in diabetes [Krause and Cramer, 1910; 

 Krause, 1910; M. R. Taylor, 1910], in phloridzin glycosuria [Cathcart 

 and Taylor, 1910], in hepatic disease [Mellanby, 1908], in phosphorus 

 poisoning [Forschbach, 1908], and in toxic fevers, mostly after the 

 crisis [Myers and Volovic, 1913]. 



Creatinine is a normal constituent of mammalian urine [Petten- 

 kofer, 1844; Fiebiger, 1903]. It is absent from muscle or present 

 only in traces (for precautions to avoid its formation from creatine in 

 extraction see Mellanby [1908] and Cabella[i9i3]). Small quantities 

 have been found in cancer tumours [Saiki, 1909] and in egg-yolk 

 [Salkowski, 1911], but the latter observation is contrary to that of 

 Mellanby [1908]. 



Neither creatine nor creatinine occurs in the urine of fish [Denis, 

 1912] nor in that of cuttle-fish [von Fiirth, 1900]. According to 



