THE CHEMISTRY OF THE ANIMAL BODY. 981 



may be considered as acetic acid in which one H atom is replaced by acetyl, 

 CH 3 CO ; or as /3-keto-butyric acid. Treated with hydrogen it is reduced 

 to ^-oxybutyric acid (CH 3 .CHOH.CH 2 .COOH), which in turn may be oxi- 

 dized to the original substance. Aceto-acetic acid readily breaks up into acetone 

 and carbonic acid : 



CHGOCHCOOH = CHCOCH + CO. 



Aceto-acetic acid, acetone, and /3-oxybutyric acid are found in the urine sometimes singly, 

 sometimes together, but only as the result of a metabolism of the body's organized proteid 

 (leucocythsemia, diabetes, fever, inanition), not of that of the proteid ingested. Indeed, 

 these substances under the above circumstances seem to appear in the urine in direct pro- 

 portion to the nitrogen present in other words, to the proteid decomposition. 1 From their 

 chemical relations already mentioned they may be regarded as of common origin, coming 

 from the proteid molecule under peculiar conditions of metabolism, and in confirmation of 

 this, Araki 2 has shown that on feeding /3-oxybutyric acid it is oxidized and aceto-acetic 

 acid and acetone may be detected in the urine. The production of the two acids seems to 

 further a gradual neutralization of the blood, ultimately causing coma. 3 In the presence 

 of these substances ammonia runs high in the urine, and in amounts proportional to their 

 excretion 4 (compare p. 993). 



Aceto-acetic acid gives to urine in the absence of phosphates a red coloration 

 with ferric chloride (principle of the reaction of Gerhardt). 



Amido-acetic Acid, or Glycocoll, CH 2 .NH 2 .COOH. This is a substance 

 obtained by boiling gelatin with acids or alkalies. It is found in human bile 

 and in that of other animals combined with cholic acid and called glycocholic 

 acid. Chittenden 5 has found glycocoll in the muscles of Pectefa irradians. 

 It is found in the urine combined with benzoic acid as hippuric acid after 

 feeding benzoic acid or compounds which the body converts into benzoic acid. 

 In a similar manner phenaceturic acid is found in the urine from the grouping 

 together of glycocoll and phenyl acetic acid. Glycocoll and urea are to be 

 obtained by the decomposition of uric acid through hydriodic acid. Glycocoll 

 forms colorless crystals, soluble in water and having a sweet taste. 



Glycocoll in the Body. If glycocoll be fed it is absorbed and appears as 

 urea in the urine. The fact that dogs, whose bile never contains glycocholic 

 acid, nevertheless excrete hippuric acid after being fed with benzoic acid, indi- 

 cates that glycocoll may be considered a normal nitrogenous decomposition 

 product of proteid. Its easy cleavage from gelatin, a product manufactured 

 from proteid in the body, confirms this. 



Amido- Adds in General. These acids, such as glycocoll. aspartic acid, glutamic acid, 

 leucin, and tyrosin are found as putrefactive products of albumin and gelatin. In these 

 acids the amido- group is very stable, and cannot be removed by boiling with KOH. They 

 are all converted in the body into the amide of carbonic acid (urea). Amido- acids may in 

 general be synthetically formed by heating mono-halogen compounds of the fatty acids with 



ammonia : 



CH 2 C1COOH + NH 3 = CH 2 NH 2 COOH'+ HC1. 



1 Wright : Grocers' Research Scholarship Lecture, London, 1891 ; V. Noorden : Pathologic des 

 Sto/wechsels, 1893, p. 178. 



3 Zeitschrift fur physiologische Chemie, 1893, Bd. 18, p. 6. 



3 Miinzer and Strasser : Archiv filr exper. Pathologic und Pharmakohgie, 1893, Bd. 32, p. 372. 



4 Loc. cit. 5 Annalen der Chemie und Pharmakohgie, 1875, Bd. 178, p. 266. 



