18 



VETERINARY PHYSIOLOGY 



these which give the biuret test — the pink or violet when 

 sodium hydrate is added to the protein with which a trace of 

 cupric sulphate has been mixed. 



The different stages of the disintegration of the native 

 protein molecule may be arranged as follows, according to 

 their reactions to heat, ammonium sulphate, and 

 alcohol : ^ — 



Native Proteins. 



Proteoses. 



Peptones. 



Polypeptides. 



Dipeptides. 

 Final Products. 



\ 



o 



For a " Classification of Proteins," see Appendix. The 

 tests for the Proteins must he learned practically. 



B. Synthesis of Proteins. — Emil Fischer and his co-workers 

 have succeeded in building up from the amino acids a series 

 of bodies containing several of the amino acid molecules, 

 linked to one another in series, the hydroxyl, OH, of 



1 For a short account of the chemistry of these products of disintegra- 

 tion, see Appendix. 



