372 CARNEGIE INSTITUTION OF WASHINGTON. 



It has been shown that an optunum proportion of some amino-acids 

 must be available in the food if a maximum rate of growth is to be 

 attained. This fact makes it of economic as well as scientific interest 

 to know the amino-acid make-up of food proteins, so that suitable 

 combinations of them may be furnished in the diet. Van Slyke's 

 method of protein analysis should furnish information respecting the 

 relative amounts of nitrogen belonging to some of the individual 

 amino-acids as well as to various groups of them. We have conse- 

 quently given attention to Ritthausen's method for precipitating the 

 total protein from extracts of food products by means of copper 

 sulphate. 



We have further devoted our efforts to determining the amount of 

 nitrogen extracted from several seeds by various solvents, as well as 

 to the conditions under which the most could be extracted. As this 

 work is preliminary to more extensive investigations, the results now 

 available will serve as a guide for future studies. 



Analyses made in Van Slyke's laboratory, showing the distribution 

 of nitrogen in gliadin and lactalbumin, did not agree, especially in 

 respect to lysine, with analyses made in this laboratory by Kossel's 

 method. Since Van Slyke's method, if reliable, should give a general 

 idea of the peculiarities of the amino-acid make-up of proteins, or 

 products rich in protein, it seemed desirable to cooperate with this 

 investigator in an effort to determine the degree of agreement to be 

 expected between results by the two methods. The outcome has 

 been a substantial agreement, secured by slightly modifying each 

 method. We have also made several other analyses by Van Slyke's 

 method in order to secure data necessary to the development of 

 methods whereby a knowledge of the characteristic features of the 

 amino-acid make-up of the total protein of food substances can be 

 obtained without too great an expenditure of time and labor. 



Work on the immunological relations of the vegetable proteins in 

 cooperation with Professor H. G. Wells has been continued. Further 

 studies of the anaphylaxis reaction between proteins from seeds of 

 different genera have shown that typical and severe reactions may 

 sometimes be obtained when proteins isolated from seeds of different 

 genera are employed. In every case such reactions have been 

 developed only by preparations of proteins so nearly alike that 

 differences between them have not been detected by physical or 

 chemical means, or else the differences found have been so slight 

 that it seems highly probable that the proteins concerned are very 

 similar in chemical constitution. Such reactions can be attributed 

 to common reactive groups in these different proteins, evidence of 

 which was given in an earlier paper dealing with the proteins of wheat 

 and barley. 



