346 ANNUAL REPORTS OF DEPARTMENT OF AGRICULTURE. 

 WORK UNDER GENERAL AUTHORIZATION. 



Under a general authorization for investigations relating to the 

 application of chemistry to agriculture, work was done on crop chem- 

 istry, on a study of the odorous principles of the cotton plant, on pro- 

 teins, on vegetable oils, on citrus fruits, on cassina, on tanning and 

 leather, on the waterproofing, mildewproofing, and fireproofing of 

 fabrics, on the utilization of cull and surplus sweet potatoes, on the 

 production of gas from straw, and on methods of analysis of agri- 

 cultural products. 



CKOP CHEMISTRT. 



Research in the chemistry of plant constituents has yielded knowl- 

 edge of tremendous value to agriculture. Upon this knowledge of 

 fats, sugars, starches, proteins, etc., great industries, which have 

 enhanced the value of the raw products of the farm, have been de- 

 veloped. A knowledge of the relation of the mineral matter in the 

 soil and in the plant to the value of the plant as food is of funda- 

 mental importance. During the year a preliminary study was made 

 of the migration of the mineral "constituents from the stalks to the 

 heads of wheat with the advancement of the growing season. Work 

 was done on a study of the lime requirement of plants and on the 

 analysis of plant materials. A study of wheat seedlmgs undertaken 

 to determine the effect of initial hydrogen-ion concentration of the 

 medium on the rate of absorption of phosphoric acid and potassium 

 is being continued. 



Although much of the research work heretofore undertaken on 

 crop production has had for its object the laudable purpose of greater 

 yield per unit, nutritive quality is of equal importance with quantity 

 of yield. Hence the chemist seeks to learn whether or not there 

 is danger of producing quantity at the serious expense of nutritive 

 quality. Work on this subject is now under way. 



ODOKOUS PRINCIPLES OF THE COTTON PLANT. 



A study of the odorous principles of the cotton plant, which are 

 presumed to attract the boll weevil, was undertaken in cooperation 

 with the Bureau of Entomology. If it should be found possible to 

 identify the odorous compounds and obtain them from some other 

 source in sufficient quantities for practical use, a method might be 

 devised for the eradication of the boll weevil which is causing wide- 

 spread destruction of cotton. The preliminary work is being con- 

 ducted at Tallulah, La., while the more detailed operations will be 

 carried on in the laboratory at Washington. 



PROTEINS. 



The most costly per unit as well as the most important constituent 

 of our foods is the nitrogenous matter. Animals are wholly de- 

 pendent, either directly or indirectly, upon nitrogenous products 

 synthesized by plants. Recent researches have shown that vegetable 

 proteins vary in composition. Some of the amino acids which con- 

 stitute the various proteins are now known to be essential to animal 



