NUTRITION. 



Osborne, T. B., and L. B. Mendel, New Haven, Connecticut. Continuation 

 and extension of work on vegetable proteins. (For previous reports see 

 Year Books Nos. 3-21.) 



In our last report we referred to studies which were in progress on the 

 water-soluble constituents of alfalfa and which we hoped might ultimately 

 lead to a better understanding of the chemistry of the cell and more specifi- 

 cally of the chemical make-up of this important forage plant. 



Although progress in this difficult field of investigation has necessarily been 

 slow, the results thus far obtained have been such as to impress us with the 

 great importance of the problems awaiting solution. Until far more is learned 

 of the chemical constituents of the cell than is at present known, plant 

 physiology and plant physics will have a very inadequate foundation. A 

 study of the literature shows how limited this knowledge is, for it is chiefly 

 confined to an enumeration of chemical substances which have been obtained 

 from many species of plants, very little being found which enables one to form 

 a conception of the relations which these bear to one another or to the meta- 

 bolic processes incident to the life of the plant. However much impressed one 

 may be by the paucity of the information obtainable from the literature, 

 attempts to deal with the mixture of substances as they occur in the plant- 

 juice impress one even more by showing how small a part of these are made 

 up of already-identified substances. One can not fail to recognize that 

 here is an almost unexplored field for future investigations. 



Naturally, in dealing with such a complex mixture of inorganic substances, 

 which in the past have received very little attention from chemists, progress 

 has been slow. Nevertheless, data have been secured which we believe to 

 be essential to the development of methods which are needed before the indi- 

 vidual constituents can be isolated and identified. 



In our last report we dealt with the proportion of different forms of nitrogen 

 present in solution both before and after hj^drolysis. We there stated that 

 from the basic constituents precipitated by phosphotungstic acid after 

 hydrolysis no arginine, histidine, or lysine could be isolated. As relatively 

 small quantities of the juice were used for these experiments, we have since 

 repeated them, using much larger quantities. 



The filtrate from the precipitate produced by adding 53 per cent, by weight, 

 of alcohol to 3,415 c.c. of the juice of the alfalfa plant was concentrated, boiled 

 with 25 per cent of sulphuric acid for 12 hours, and the basic products of 

 hydrolysis precipitated with phosphotungstic acid. By employing Kossel's 

 method for determining the basic amino acids produced by the hydrolysis of 

 proteins we found that the silver-baryta precipitate yielded arginine contain- 

 ing nitrogen equal to 3.6 per cent of the nitrogen present in the filtrate from the 

 precipitate from the 53 per cent alcohol precipitate. This was identified as 

 the picrolonate. 



Another substance yielding a crystalline hydrochloride, which did not give 

 the reaction with diazo-benzene sulphonic acid characteristic of histidine, 

 formed most of the precipitate produced by HgS04. When converted into the 

 picrate, this melted sharply at 298°. If histidine is present among the bases, 

 its proportion must be very small. The amount of the above substance was 

 340 



