HISTORICAL REVIEW 3 



of coagulable protein in the juices of various parts of many plants, and 

 described the method by which he obtained preparations of what he 

 supposed to be pure plant albumin. This he found to have all the 

 properties of animal albumin, and he gave an account of a comparison 

 of these two substances. This observation of Fourcroy was the first 

 to demonstrate the presence of two kinds of protein in plants. 



From 1799 to 1805 albumin was found in the juices of many plants 

 and in the sap of trees by a number of different investigators, who, 

 however, added but little to the information which had been furnished 

 by Fourcroy (cf. 91, 559, 182, 554, 62, 123, 385, 386, 555, 63, 556). 



In 1805 Einhof (105) discovered that a part of the gluten of wheat 

 was soluble in alcohol, and described the existence of similar proteins 

 in rye (105) and barley (106). He, however, assumed that all of the 

 gluten of wheat was soluble in alcohol, and considered this to be a 

 characteristic property of all vegetable proteins except the albumin, 

 which occurred dissolved in the juices of plants. He also undertook 

 an extensive investigation of the constituents of the potato (104), 

 barley (106), peas and beans (107) and lentils (108), and found that the 

 leguminous seeds contained a form of protein which was not soluble in 

 alcohol or in water. He assumed that this belonged to a distinctly 

 different group of substances, although he recognised that it was related 

 to the gluten which he had found in the seeds of the cereals. His dis- 

 coveries showed the presence of two new forms of protein matter in 

 plants and laid the foundation for a more extended knowledge of these 

 substances. 



In 1 809 Gren ( 1 4 1 ) in his Grundriss der Chemie, in reviewing the liter- 

 ature of vegetable proteins, stated that gluten contains carbon, hydrogen, 

 nitrogen, phosphorus and calcium, for by distillation it yields products 

 which contain these elements. He further stated that plant albumin 

 contains hydrogen, nitrogen, carbon, sulphur, oxygen and probably cal- 

 cium phosphate, and cites as his authority the analyses by Fourcroy and a 

 then recent paper by Jordan. He does not mention, however, the nature 

 of the evidence given by these latter investigators from which this com- 

 position of plant albumin was deduced, and as he makes no reference 

 to the original publications by either of these authors, it has not been 

 possible to determine the basis for his statement, which appears to be 

 the first publication in regard to the ultimate composition of vegetable 

 proteins. 



During the next ten years little advance was made beyond an addi- 

 tion to the number of seeds in which such substances were found (cf. 

 53, 180, 511, 557, 227, 558, 50, 387, 565). 



