PREFACE. 



ALTHOUGH the proteins of plants early claimed the attention 

 of many chemists, our present knowledge of them has not 

 yet advanced beyond what is, in fact, a mere beginning of a 

 serious study. The isolation and purification of vegetable 

 proteins present so many difficulties that for a long time the 

 available methods were too crude to enable those who under- 

 took such work to succeed in their task. The development 

 of the methods used by physiological chemists in their investi- 

 gations of animal tissues, the great development of organic 

 chemistry, and the no less important knowledge of the use of 

 antiseptics and the action of enzymes has only recently made it 

 possible to prosecute a study of the vegetable proteins with a 

 reasonable prospect of success. 



A knowledge of the vegetable proteins is in many ways of 

 importance to the animal physiologist, but the latter has had 

 so many rapidly increasing lines of research opened to him 

 during the past few years that he has had little time to give 

 to the literature of the vegetable proteins. The writer has, 

 therefore, thought it more important to devote the limited 

 space of the present monograph to a discussion of the general 

 chemical and physical properties of the vegetable proteins than 

 to give a descriptive account of the individual proteins at 

 present known. It is hoped that by this method of presenta- 

 tion the opportunities offered by the vegetable proteins for 

 obtaining a more definite knowledge of the properties of protein 

 matter in general will be better appreciated, and that in the 

 future the studies of vegetable and animal proteins will be 

 brought into closer relations than in the past. 



