THE CHEMISTRY OF THE ANIMAL BODY. 1021 



cannot be classified here. A list of the principal products of the digestion 

 and putrefaction of proteid may not be out of place. It includes albumoses, 

 peptones, leucin, tyrosin, lysin and lysatinin, aspartic acid, glutarnic acid, amido- 

 valerianic acid, volatile fatty acids ; phenyl-propionic, phenyl-acetic, p-oxy- 

 phenyl-acetic, and p-hydrocumaric acids ; p-cresol, phenol, indol, skatol ; and 

 the gases, ammonia, carbonic oxide, sulphuretted hydrogen, methyl mercaptan, 

 hydrogen, and methane. 



The size of the proteid molecule must be very great, and one computation 

 shows the following figures : l 



Egg-albumin. Proteid from haemoglobin (dog). 



It is well, perhaps, finally, to speak of experiments which, however incom- 

 plete, at least throw some light on the possibilities of the problem of the syn- 

 thesis of proteid. Lilienfeld 2 through the condensation of the ethyl-ester of 

 glycocoll has obtained a body insoluble in water, but swelling in it, forming a 

 gelatinous mass. The substance gives the biuret reaction, is insoluble in 

 alcohol and dilute hydrochloric acid, but dissolves in pepsin-hydrochloric 

 acid. These reactions show its kinship to gelatin. Lilienfeld likewise de- 

 scribes a synthetically formed peptone and a coagulable proteid, 3 the peptone 

 formed principally through condensation of the above-described product with 

 the ethyl-esters of the amido- bodies, leucin and ty rosin, the proteid from the 

 same with addition of formic aldehyde. Grimaux likewise has produced, 

 with other reagents, colloids which resemble proteids. Probably none of 

 these substances are native proteids, but they furnish indications of lines of 

 attack for the future mastery which in time is sure. 



1 Bunge : Physiologische Chemie, 3d ed., 1893, p. 56. 



2 Verhandlungen der Berliner physiologischen Gesellschaft, Archiv fur Physiologic, 1894 r 

 p. 383. 



3 Ibid., p. 555. 



