498 THE POPULAR SCIENCE MONTHLY 



abundant meat supply is to be maintained, it must be in some other 

 way. With such a density of population as we may reasonably expect, 

 it will no longer be a question of producing bread or meat, but of pro- 

 ducing bread and meat. All the edible products which the farmers' 

 acres can yield will be needed for human consumption and the function 

 of the stock feeder in a permanent system of agriculture will be to 

 utilize those inedible products in which so large a share of the solar 

 energy is held and to render at least a portion of the latter available 

 for human use. Meat and other animal products will be produced, not 

 as luxuries for the tables of the rich, but as a means of conserving 

 energy for human use, both directly through the food thus rescued 

 from waste and indirectly by setting free edible plant products for man's 

 use. The stock feeding of the future will be a very different matter 

 from the simple grazing of cattle in summer or the lavish feeding of 

 corn in winter. It will be a highly artificial process, dealing with 

 feeding stuffs unfamiliar to the fathers and seeking to utilize to the 

 utmost the energy of every available by-product. It will call for a de- 

 gree and a kind of knowledge and skill far exceeding that which has 

 sufficed in the past. 



Until within a comparatively few years, but little direct study has 

 been devoted to these fundamental considerations, especially in the 

 United States. While institutions for agricultural research have flour- 

 ished, they have either concerned themselves with the more obvious 

 problem of increasing crop production or else, in response to the de- 

 mands of stockmen, have devoted their energies largely to seeking more 

 efficient ways of converting corn into meat. In this latter respect, they 

 have aided in exploiting rather than in conserving food resources, and 

 it has been difficult to secure public interest or public funds for funda- 

 mental investigation looking toward the conservation of the food supply 

 of the future. 



More than a purely scientific interest, therefore, attaches to studies 

 of the principles governing the utilization of the stored-up energy of 

 feeding stuffs, particularly of by-product feeds, such as have been made 

 during the past ten or twelve years by German investigators, particu- 

 larly by Kellner at the Moeckern Experiment Station, and as are now 

 being prosecuted by the Institute of Animal Nutrition of the Pennsyl- 

 vania State College in cooperation with the Bureau of Animal Industry 

 of the United States Department of Agriculture. 



Such a study is far from being a simple matter. Essentially, of 

 course, its method must consist in feeding the products under investi- 

 gation to animals and ascertaining what proportion of their energy can 

 be thus saved. The difficulty lies in the determination of the latter 

 point. This must be accomplished with an accuracy and a degree of 

 detail unattainable in the ordinary feeding experiment if the conclu- 



