THE PROTEINS OF THE WHEAT KERNEL. 



INTRODUCTION. 



Of the protein substances used as food none is of more importance than 

 those contained in the seeds of wheat. Although these bodies attracted 

 the attention of investigators more than one hundred years ago and have 

 since then been many times the subject of study, the published statements 

 respecting them are so conflicting and uncertain that it has heretofore been 

 impossible to know what the truth regarding them actually is. With the 

 purpose of clearing up the existing confusion and determining the real 

 value of the evidence offered, as well as extending, as far as possible, our 

 knowledge of these important substances, the writer some years ago under- 

 took an investigation of this seed which has recently been concluded by 

 work done under grants from the Carnegie Institution of Washington. As 

 the results of these investigations have been published from time to time in 

 a number of different papers, appearing in four different journals, it has 

 been thought desirable to bring all this work together in one paper. In so 

 doing the details have been reproduced in full, for the nature of the evidence 

 is such that its value largely consists in concordant results of many experi- 

 ments, repeated under different conditions, since it is not yet possible to 

 establish the chemical individuality of different protein substances by demon- 

 strating their possession of definite physical properties, as may be done with 

 the simpler organic compounds. 



The experience of the writer in his endeavors to understand and repeat 

 the work of many of his predecessors has made him feel the importance of 

 these details to future workers along the same lines and is his excuse for 

 giving with so much minuteness the results of his own work, which to those 

 not familiar with the difficulties of the subject must appear to a large extent 

 unnecessary. In order to make this work available to those who wish sim- 

 ply to know the results, a comprehensive summary of this paper is given at 

 the end of this publication, and the details of the many operations and experi- 

 ments need be read only by those who wish to become familiar with these. 



The account of this work is preceded by a review of the literature of the 

 subject, from which an idea of the unsatisfactory state of our previous 



5 



