NUTRITION. 



379 



suitable for further study, rather than to the isolation of individual chemical 

 compounds. As a preliminary to this examination, careful analyses have been 

 made of the ashes of the "colloid precipitate," the precipitate produced by 

 adding 53 per cent of alcohol to the filtrate from the "colloid precipitate," 

 and of the solids of the filtrate from the latter precipitate. We have thus 

 established the relative proportions of each of the inorganic ions in these three 

 fractions. No evidence was obtained that any considerable part of these 

 elements was in organic combination. It was thus found that addition of 

 53 per cent of alcohol to the clear alfalfa press juice removed considerably 

 more than half of the inorganic constituents and left only a small part of the 

 calcium, phosphoric acid, or sulphuric acid in the solution. 



The filtrate from the 53 per cent alcohol precipitate, which contains about 

 half of the nitrogen of the alfalfa juice, presents an opportunity for obtaining 

 a better knowledge of its nonprotein nitrogenous constituents than we now 

 have. Although these undergo continuous changes during the growth of the 

 plant and can therefore not be dealt with from a quantitative, or even a 

 qualitative, standpoint, with any high degree of accuracy, nevertheless we 

 have obtained analytical results with different lots of plants which agree more 

 closely than we at first expected and give a general picture of the types of 

 compounds present in the juice which should ultimately contribute to a better 

 knowledge of these substances than we now have. 



Thus, by applying Hausmann's method for determining "ammonia," 

 "humin," and "basic" nitrogen, and Van Slyke's method for amino nitrogen, 

 we obtained the following results with three different lots of alfalfa plants, 

 expressed in percentages of the total nitrogen: 



In view of the fact that these methods were primarily designed for applica- 

 tion to the products of protein hydrolysis, as well as to the fact that these 

 three lots of alfalfa were not of precisely the same age, the agreement between 

 these analyses is sufficiently close to justify useful conclusions. 



Before hydrolysis, ammonia salts are present in relatively small proportion 

 and substances containing nitrogen converted into ammonia by hydrolysis 

 are present in no inconsiderable amount. Basic substances, precipitable by 

 phosphotungstic acid, contain from 40 to 50 per cent of the water-soluble 

 alfalfa nitrogen which by hydrolysis is reduced to about one-half as much, 

 presumably largely through the loss of nitrogen which is converted into am- 

 monia and "humin" nitrogen. Thus the sum of the basic "humin" and of the 

 increase in ammonia nitrogen is respectively 43.1, 46.7, and 45.1 per cent of 

 the total nitrogen, which figures do not differ very widely from the basic 



