THE PRODUCTS OF ALBUMINOUS DIGESTION. 



obtained, which is then dissolved in boiling water and digested with 

 an excess of carbonate of copper, as before. The hot filtrate is 

 again concentrated, when on standing the copper salt of asparaginic 

 acid separates out in characteristic groups of needles. The filtrate 

 is freed from copper by means of hydrogen sulphide, concentrated, 

 and set aside, when the glutaminic acid crystallizes out. 



Glycocoll. While it is generally known that glycocoll plays an 

 important part in the nitrogenous metabolism of the animal body,, 

 and is intimately concerned in the formation of urea, hippuric acid,, 

 phenaceturic acid, certain biliary acids, and in birds and reptiles of 

 uric acid, it is of interest to note that the substance has thus far 

 not been found as such among the products of pancreatic digestion, 

 although its radicle is manifestly present in certain albumoses. On 

 hydrolytic decomposition with mineral acids, on the other hand, 

 glycocoll can be obtained from most albumins, but is especially 

 abundant in collagen, viz., gelatin. Two exceptions to this general 

 rule, however, are noted, viz., casein and (according to Magnus- 

 Levy) the peculiar albuminous substance which is known as the 

 Bence Jones 7 body, and from either of these it is also impossible to 

 obtain a heter-o-albumose. The hetero-albumose of fibrin, according 

 to Spiro, yields a considerable amount of glycocoll, while from the 

 proto-albumose it cannot be obtained. 



Heretofore the isolation of glycocoll and its recognition as such 

 were attended with great difficulties. A somewhat simpler pro- 

 cedure, however, has recently been suggested by Baum, and with 

 its aid Spiro was able to show that, contrary to former views, the 

 substance can be obtained not only from the albuminoids, but also 

 from the native albumins, with the exceptions indicated. The 

 method is based upon the observation that glycocoll can be trans- 

 formed into hippuric acid in the test-tube by treating with benzoyl 

 chloride in the presence of sodium hydrate, and that the formation 

 of the resulting hippuric acid can be readily demonstrated by con- 

 densing this with benzaldehyde in the presence of sodium acetate 

 and acetic anhydride. The lactimide of benzoyl-amido-cinnamic 

 acid is thus formed. On decomposition with sodium hydrate this 

 yields phenyl-pyro-racemic acid, which in ethereal solution gives a 

 green color on treating with chloride of iron. With plienyl- 

 liydrazin, moreover, it forms an osazon which melts at 161 C. 

 These changes may be represented by the equations : 



(1) CH 2 .(NH 2 ).COOH -f C 6 H 5 .COC1 = CH 2 .NH(C 6 H 5 .CO).COOH + HC1 



Glycocoll. Benzoyl chloride. Hippuric acid. 



(2) CH 2 .NHfC r H 5 .CO).COOH 4- C 6 H 5 COH = C 6 H 5 .CO.N.C:CH.C 6 H 6 



Hippuric acid. Benzaldehyde. 



CO 



Lactimide. 



(3) C 6 H 5 .CO.N.C:CH.C 6 H 5 + H 2 O = C^ 5 .CO.NH 2 .C.0 6 H 5 .CH.COOH 



/ Benzoyl-amido-cinnamic 



CO acid - 



Lactimide. 



