624 Journal of Agricultural Research vol. xx, No. s 



the form of protein nitrogen. Eighty-one per cent of the nitrogen in the 

 tubers proved to be soluble — that is, appeared in the pressed juice of 

 the potato. The sprouts contained 1.5 per cent of nitrogen on a dry 

 basis. In 1880 these same investigators (/o) isolated leucin and tyrosin 

 from an alcoholic extract of potato sprouts. Osborne and Campbell (7) 

 obtained a globulin called "tuberin," the properties of which they de- 

 scribe, and a small amount of another protein from potato. Sjollema 

 and Rinkes (11) have studied the hydrolysis of potato protein. They 

 precipitated the protein with a saturated sodium -chlorid solution, dis- 

 solved it in 10 per cent sodium chlorid, dialyzed it to remove the salt, 

 and finally reprecipitated it with alcohol. The nitrogen content of the 

 protein obtained was 14.9 per cent. Their investigation was divided as 

 follows : (1) Estimation of the various diamino acids (Van Slyke method) ; 

 (2) hydrolysis of protein by hydrofluoric acid; (3) estimation of different 

 diamino acids (Kossel and Patten method); (4) estimation of momo- 

 amino nitrogen by Fisher's esterfication method; and (5) estimation of 

 tyrosin. The result of their study of the hydrolysis of potato protein 

 showed that 100 gm. contained nitrogenous substances distributed as 

 follows : 



Gm. 

 Ammonia 1.8 



Histidin 2 



Arginin 4 



Lysin 3 



Cystin 4 



Glutaminic acid 4 



Prolin 3 



Gm. 



Alanin 4. q 



Leucin 12 



Valin 1 



Valin and alanin 8 



Valin and leucin 1. 9 



Phenylalanin 3.9 



Tyrosin 4. 3 



Ramsay and Robertson (8) have reported data on the rate of assimi 

 lation of food from the soil by the potato plant and the relative pro- 

 portion of each of the principal elements contained in the plants. 



The fact that Bordeaux-sprayed potato plants in certain localities give 

 larger yields of tubers than unsprayed plants has been established by a 

 series of experiments extending over many seasons at the Vermont, 

 Maine, and New York Agricultural Experiment Stations. Stewart, 

 Eustace, and Sirrine (12), of the New York Experiment Station, reported 

 several years ago that one lot of Bordeaux-sprayed tubers was higher 

 in solids and starch than a corresponding lot of unsprayed tubers. 

 Charles D. Woods, of the Maine Experiment Station, has reported simi- 

 lar findings (13). The writer has analyzed several samples of Bordeaux- 

 sprayed and unsprayed tubers grown in Maine during the past three 

 seasons, generally finding a higher content of solids and nitrogen in the 

 sprayed than in the unsprayed tubers. 



