82 PRINCIPLES OF PHYSIOLOGY 



Of the true chemical structure of proteins 

 we know little, but it has been shown that 

 by various agencies they split up into numer- 

 ous simpler bodies which also may be arranged 

 in groups. There seem, as it were, to be 

 lines of cleavage, so that the complex pro- 

 teins, under the influence of acids, alkalies, 

 high temperatures, and various enzymes, 

 decompose into acids, bodies of a fatty 

 nature, aromatic bodies, which all contain 

 nitrogen, and bodies that belong to the carbo- 

 hydrate group, containing no nitrogen, such 

 as starch and sugar. Such bodies are pro- 

 duced when proteins are split up, whether 

 it be by the processes of the chemist in the 

 laboratory, in the process of digestion under 

 the action of the digestive enzymes, or in 

 putrefaction as carried on by many micro- 

 organisms, and more especially by the Bac- 

 terium termo, a minute organism found 

 wherever there is decay. Proteins are ulti- 

 mately resolved into certain ammoniacal 

 compounds and urea, a substance abundant in 

 the urine. 



40. The carbo-hydrates are the starches 



