THE DECOMPOSITION PRODUCTS OF 



PROTEIDS. 



\ N intimate knowledge of the constitution of Proteids 

 xY would lead to such important and far-reaching- physi- 

 ological results, that many observers have been induced to 

 undertake lengthy investigations with a view, if possible, 

 to solve or to throw some light upon this difficult problem. 

 A question such as this, purely chemical as it is in its 

 bearings, must be attacked from a chemical standpoint by a 

 study of the cleavage products of proteids, and just as our 

 knowledge of simpler organic bodies is only placed upon a 

 sure basis by a successful synthesis, so, too, the constitution 

 of the proteid molecule can only be finally and satisfac- 

 torily determined by the synthesis of albuminous sub- 

 stances. Before this can be effected it is, however, 

 necessary to ascertain what substances are formed, and 

 the quantities in which they are produced by the dis- 

 integration of various proteids. 



It is chiefly to a study of this nature that experimenters 

 have as yet applied themselves. At the outset we may 

 classify the experiments as falling into two main groups, 

 the first designed with a view to determine the series of 

 changes a proteid undergoes during its transit through the 

 body, the second with the object of investigating the 

 chemical substances produced as cleavage products by 

 artificial means in vitro. In the first category the pro- 

 gress made has been but slight, because of the great and 

 obvious difficulties encountered at every step. We know 

 the end products of the full series of changes, viz., carbonic 

 anhydride and water from the carbon and hydrogen re- 

 spectively, and from the nitrogen urea, uric acid, ammonia, 

 and other more complex nitrogenous products, occurring 

 either in small quantities or only under special conditions. 

 These result from changes within the tissues and cells of 

 the body, but with regard to the intermediate substances 

 occurring between these at the one extreme, and the com- 



