804 EXPERIMENT STATION EECORD, 



The consideration of such data as the foregoing and many other 

 observed facts which have a bearing on the question lead ahnost in- 

 evitably to the conclusion that protein requirement and ash require- 

 ment are in some wa}^ interdependent. No problem concerned with 

 nutrition has been more generally discussed than that of protein re- 

 quiremeiit, and perhaps there is nowhere a greater variety of opinion. 

 For this reason It has been often said that the question could not be 

 settled until more experimental evidence was forthcoming. It seems 

 very probable that when the body demands for ash constituents are 

 thoroughly understood physiologists will be in a better position to 

 explain some of the apparent contradictions regarding protein re- 

 (juirement and other perplexing questions which have to do with the 

 kind and amount of nitrogenous material needed for the body under 

 different conditions. 



A consideration of questions such as those referred to above makes 

 it obvious that no field promises more in the way of results to the 

 experiment station investigator than that concerned with the mineral 

 constituents of agricultural products and their relation to the nutri- 

 tion and growth of the plant and the animal. Many of the experi- 

 mental methods used in the past in the determination of ash con- 

 stituents Avere faidty and the results were not very reliable. Methods 

 have, however, been improved and perfected, and difficulties which 

 were formerly encountered may now be obviated. 



Problems which suggest themselves are very numerous, including 

 such as the relation of fertilizers to the growth and development of 

 plant tissue with reference to the composition of different parts of 

 the plant, the laws of growth and of development of the animal with 

 special reference to the influence of the mineral and other constituents 

 supplied by different feeding stuffs, and many other similar problems. 



A survey of the experimental work in the general field of animal 

 production makes it apparent that while the numerous feeding ex- 

 periments which have been carried on have contributed a great deal 

 which was valuable from the standpoint of practical feeding they 

 have not supplied a proportionate amount of data of importance in 

 discussing fundamental laws of nutrition. Up to the present time 

 the study of feeding problems has been more often a comparison of 

 feeding stuffs, of different rations, or of different methods of care 

 and management, than a study of the principles which underlie such 

 questions. The Avork done has been well worth wdiile and has served 

 its purpose admirably, but it has been apparent for some time that 

 the limits of usefulness of such methods of study were being ap- 

 proached and that experiments of a different character must be under- 

 taken. Fortunately, the Adams fund makes possible a great exten- 

 sit)n of the scientific work of the experiment stations, and it is to be 



