Chap, vi The Metabolic Processes 393 



share in the formation. On the whole his researches con- 

 firmed the work of Rendle. On the other hand Belzung, 

 in 1891, supported the views of Pfeffer, suggesting that 

 all the appearances may be explained by a process of 

 precipitation of protein existing in soluble combination 

 with alkaline phosphates in consequence of the develop- 

 ment of dilute organic acids. Belzung's description of 

 the appearances attending the formation in his material 

 coincided, however, fairly well with Rendle's observations, 

 particularly as to the points of origin of the grains and 

 their final structure. Like Rendle, Belzung worked chiefly 

 on leguminous seeds. 



The various proteins which enter into the composition 

 of aleurone grains were investigated by several writers, 

 whose results were very far from concordant. This is 

 not at all surprising, as the whole question of the com- 

 position and reactions of protein substances was the object 

 of much inquiry by chemists and physiologists alike during 

 almost the whole of the period with which we are concerned. 

 The progress of knowledge of this very difficult subject was 

 very gradual, and though much advanced cannot be held 

 to be complete at present. 



The subject had attracted, in 1859, the attention of Denis, 

 who employed successfully as an extracting solvent a 10 

 per cent, solution of common salt, which had been used 

 in the preparation from animal tissues of the proteins 

 known as globulins. His work was extended in 1867 by 

 Hoppe Seyler, who prepared members of this class from 

 the Brazil nut, and from the seeds of several other plants, 

 including oats, maize, peas, almonds, and mustard. He 

 found them to resemble very closely the globulins of animal 

 origin. 



The next observations of importance were made by Ritt- 

 hausen in 1872. Abandoning the methods of his prede- 

 cessors, he used as extractive agents water, dilute solutions 



