THE CHEMICAL UNITY OF LIVING BEINGS. 179 



acterization and specification of the proteids required 

 in the first place a knowledge of two particular com- 

 pounds, the nucleins and the histones. This did not 

 become possible until after the researches of Miescher 

 and Kossel on the nucleins, which went on from 1874 

 to 1892, and those of Lilienfeld and d'Yvor Bang on 

 the histones, from 1893 to 1899. The complete 

 albuminoids are constituted by the combination of 

 two kinds of substances — albumins or histones on the 

 one hand, and nucleins on the other. By combining 

 solutions of albumins or histones with solutions of 

 nuclein, the synthesis of the proteid is effected. The 

 study of the properties and characteristics of these 

 nucleo-albumins and nucleo-histones is going on at 

 the present moment. It is being carried out with 

 much method and with wonderful patience by the 

 German school. 



All the proteids contain phosphorus in addition to 

 the five chemical elements, carbon, oxygen, hydrogen, 

 nitrogen, and sulphur, which are common to the 

 other albuminoids. Another interesting feature in 

 their history is that the action of the gastric juice 

 divides them into their two constituents: — the nuclein, 

 which is deposited and resists the destructive action 

 of the digestive liquid, and the albumin or histone, 

 which on the contrary experiences this action with 

 the usual consequences. Thus the gastric juice 

 furnishes a process which is very simple and very 

 convenient in the analysis of the proteids. 



Localization of the Nudeo-Proteids. — What we said 

 before as to the important physiological role of the 

 cellular nucleus may arouse the expectation that in it 

 will be found the living matter which is chemically 

 the most differentiated, the albuminoids of highest 



