994 AN AMERICAN TEXT-BOOK OF PHYSIOLOGY. 



corresponds normally to the amount of creatin contained in the meat food ; in 

 starvation urine it is proportional in amount to the proteid (muscle) destroyed, 

 being present even on the thirtieth day (experiment on Succi 1 ); and it is 

 present only in traces, or not at all, in the urine of milk-fed children (creatin- 

 free food). In convalescence creatin is said to be retained, possibly for the 

 building of new muscle. 2 There is no reason for believing that much creatin 

 is ever formed in the body. 



Creatin gives its flavor to meat. If gently heated it gives the odor of roasting beef. 

 Creatinin in the urine reduces alkaline solutions of copper salts (care must be taken, there- 

 fore, in making the sugar test after using meat extracts). The action of creatin is simply that 

 of a pleasant-tasting, pleasant-smelling substance, which prepares the stomach for food 

 but has no nourishing value per se. It is considered by some to be a nerve-stimulant. 



Creatinin, or Glycolyl Methyl Guanidin. Heating creatin with acids 

 changes it into creatinin with loss of water, and having the formula 



NH CO 



HN :C ( | Warming at 60 with phosphoric acid causes this 



X N(CH 3 )CH 2 



conversion. In like manner when the kidney prepares an acid urine, creatin 

 becomes creatinin : if the acid reaction be effaced through feeding alkaline 

 salts the creatin is excreted unchanged. 3 Creatinin with chloride of zinc 

 forms a characteristic very insoluble white powder of creatinin zinc chloride, 

 (C 4 H 7 N 3 O) 2 .ZnCl 2 . 



Lysatin, C 6 H 13 N 2 O 2 , and Lysatinin, C 6 H n N 3 O 2 . These substances are 

 obtained, like lysin (see below), from the hydrolytic cleavage of proteid, as for 

 example from casein or conglutin heated with hydrochloric acid and zinc 

 chloride ; they are probably likewise produced in trypsin digestion. 4 



According to Drechsel e they are homologues of creatin and creatinin, and 

 therefore should yield urea on heating with barium hydroxide. This is 

 Drechsel's method of direct production of urea from proteid by hydrolytic 

 cleavage. 



Diamido- Fatty Acids. Of these four have been described : 



Diamido-acetic Acid, CH(NH 2 ) 2 COOH. This was found by Drechsel 6 among other 

 compounds after heating casein in sealed tubes with concentrated hydrochloric acid at 140- 

 Diamido-propionic acid has not been found in the body. 



Diamido-valeric Acid, or Omithin, C 4 H 7 (NH 2 ) 2 COOH. This has been detected by 

 Jaffe in the urine and excrements of fowls. 



a-e-Diamido-caproic Acid, or Lysin, CH 2 NH 2 CH 2 CH 2 CH 2 CHNH 2 - 

 COOH. This is a hydrolytic cleavage product of casein after boiling with 

 hydrochloric acid, or baryta water, 7 and may be similarly obtained from gela- 



1 Luciani : Das Hungern, Leipzig, 1 890, p. 144. 



2 Von Noorden : Pathologic des Sto/wechsels, 1893, p. 169. 



3 Voit : Zeilschrift fur Biologie, 1868, Bd. 4, p. 150. 



4 See Drechsel, and his pupils Fisher, Siegfried, and Hedin : Archivfur Physiologic, 1891, p. 

 248 et seg. 



5 Op. oil., p. 261. 6 Abstract in Maly's Jahresbericht uber Thierchemie, 1892, p. 9. 

 7 Drechsel : Archivfur Physiologic, 1891, p. 248. 



