HISTORICAL REVIEW 5 



teins of plants. By means of their then newly developed method for 

 determining nitrogen, they were able to clearly establish differences in 

 the elementary composition between many of the proteins, and they 

 showed that these differences were particularly great in the case of 

 some of the vegetable proteins. The identity which Liebig (223) as- 

 sumed to exist between the vegetable and animal proteins was thus 

 disproved and the further accurate study of the proteins of vegetable 

 origin became a matter of importance. 



Little was done during the next ten years to materially advance 

 the knowledge of vegetable proteins, but in 1855 Hartig (148, 149) 

 published the results of his elaborate investigations of seeds, in which 

 he showed that a large part of the reserve protein was present in the 

 cells in the form of crystals and grains of more or less definite structure. 

 This discovery was followed three years later by Maschke's (267, 268) 

 announcement that he had succeeded in artificially crystallising the pro- 

 tein of the Para or Brazil-nut, which Hartig had shown to be present 

 in this seed in the form of rhombohedral crystals. 



In 1859 Denis (88) showed that many protein substances of both 

 animal and vegetable origin were soluble in neutral saline solutions, 

 and this presented to chemists an entirely new means for isolating and 

 purifying these substances. Although Denis' discovery has since been 

 of fundamental importance in the modern study of proteins, especially 

 those of seeds, its importance was not appreciated for several years. 



In 1860 Ritthausen (396) began the first serious study of the 

 vegetable proteins, and devoted himself for many succeeding years to 

 the production of preparations of the highest attainable purity, and to 

 accurate determinations of their composition. As a result of these in- 

 vestigations the prevailing knowledge was greatly extended, and it be- 

 came plain that these substances occurred in many diverse forms in the 

 different seeds. Ritthausen's work, therefore, furnished the first broad 

 foundation for a knowledge of the vegetable proteins, and the service 

 which he rendered in developing this field of knowledge deserves far 

 more recognition than it received during his lifetime. 



In 1876 Weyl (569, 570) applied to seeds the method of extraction 

 by solutions of neutral salts which Denis (88) had proposed in 1858, 

 and showed that a large number of different seeds contained protein 

 soluble in saline solutions, and that this protein had properties similar 

 to the globulins of animal origin. These vegetable globulins he 

 divided into two groups, the myosins and vitellins, according as they 

 were insoluble or soluble in saturated solutions of sodium chloride. 

 The views which he advanced in respect to the general character of 



