108 EXPERIMENT STAllON EECOED. 



been the subject of extensive experiments. In addition to these more 

 directly i^ractical experiments, the functions of food in the animal 

 body, its physiological requirements, and the comparative effects of 

 nutrients from different sources have received much study. These 

 mark the latest advancement in feeding investigation. 



In the physiology of nutrition, two lines of work are showing 

 special activity at the present time — the study of mineral nutrition 

 and of the relative efficiency and adequacy of proteins from different 

 sources. This illustrates again the tendency of all agricultural re- 

 search toward greater precision and definiteness. 



For many years the problems of animal nutrition were studied 

 without much regard to the function or the requirements of minerals 

 in feeding stuffs, but later investigation has shown the question of 

 mineral balance in animal rations to be one of great importance. The 

 only difference formerly recognized in the constituents of different 

 feeding stuffs, including the protein, was a difference in digestibility. 

 But when the proteins from different sources came to be isolated and 

 studied their constitution was found to differ materially and also 

 their effect in tlie nutrition of the animal. This has shaken the old 

 confidence in the more analysis of feeds as indicating their value in 

 animal feeding. The proof has already been furnished that the con- 

 stitution of the protein molecule is of fundamental importance in 

 determining its nutritive efficiency, some of these compounds being 

 quite defective for maintaining life, while others are highly efficient. 

 The scientific basis of these differences is gi'adually being established, 

 and in the meantime caution is exercised in the calculation of rations 

 on the mathematical basis. 



It is only necessary to refer to the gi-eat amount of study of 

 injurious insects and pests, the large number of plant diseases and 

 other affections, and the successful devising of means for their con- 

 trol or eradication to show what a storehouse of directly available 

 information of the most practical sort is noAV at hand. The differ- 

 ence between intelligent control of these pests and their inirestrained 

 action means many millions of dollars in crops alone. The case is 

 similar with animal diseases, where we are told that the country 

 suffers a loss of $212,000,000 annually in live stock from diseases 

 which are now understood and preventable. 



In dairying the work of the stations has largely revolutionized tlie 

 industry, and furnishes a basis which needs only to be applied to 

 work even greater benefits. 



In some respects the development of knowledge has made the sta- 

 tion worker less sure of theories than before, and more prone to 

 caution in presenting them as a basis for practical action. It will 

 be for the experiment station to exert its influence in combating over- 



