No. 6. DEPARTMENT OF AGRICULTURE. 669 



of vinegnrand othor formontation products have been made possible 

 by the joint ell'or(s of the chemist and the baeteriolo<;ist. Tlie opera- 

 tions of the creamery, to-day, are alike a monument lo mecluinical 

 and chemical genius; where twenty-five years ago, over one-fourth of 

 the milk fat was thrown to waste in the skimmed milk, and a large 

 additional fraction was lost in the buttermilk, the losses of to-day's 

 operations have been reduced to one-tenth of that which was com- 

 mon in 1S75; the introduction of methods of chemical analysis to 

 govern the exactness of operations of the new mechanical appliances 

 for cream separation and chuiiiing has made this possible. 



It mav fairlv be claimed, also, that a verv large measure of that 

 development of agricultural science in the fields of plant physiology, 

 animal industry, veterinary science and general agricultural practice 

 that has resulted from the work of investigators in those lines at the 

 various agricultural experiment stations of the world, is due very 

 largely to the stimulus which the study of chemical problems for the 

 promotion of agriculture gave. The primary work of nearly all the 

 experiment stations that have been established, and certainly that 

 of the first stations established, has been chemical in nature. The 

 mere fact that laboratories, where special appliances and peculiarly 

 trained men are necessary for chemical research, made the establish- 

 ment of such stations inevitable. Once established, the inauguration 

 of parallel lines of investigation by the botanist, agriculturist, veter- 

 inarian and the bacteriologist naturally followed. 



What w'ork the next century shall see accomplished in agricul- 

 tural chemistry, the boldest would scarce venture to predict. From 

 the present standpoint the most pressing needs seems to be for in- 

 vestigation on five classes of subjects: First, the value of its several 

 mineral constituents to the plant; second, the nature of the appar- 

 ent selective power which plants manifest in the taking up of food 

 materials from various mineral sources; third, the formulation of 

 m(>thods of analysis, by which the average selective action of a given 

 crop upon the soil may be imitated in the laboratory for the purpose 

 of afl'ording, through analysis, the means of more precise determina- 

 tion of the specific crop-producing value of soils; fourth, the better 

 separation of the several constituents of plants and, fifth, the deter- 

 mination of their respective food values to the animal. 



