fl. V. Akmsbyanp.I. a. Fries 183 



Furthermore, similar trials were made with nearly pure gluten, starch, 

 cellulose, sugar and oil as representatives of the digestible protein, 

 carbohydrates and fats of feeding stuffs, and from their results, corrected 

 by those on actual feeding stuflFs, a method was worked out for computing 

 the energy values of materials not yet subjected to respiration experi- 

 ments. The details of the method of calculation have been frequently 

 published' and need not be reproduced here. The writers, following, 

 as already stated, the same general plan of investigation but determining 

 the actual heat production of the experimental animal as well as its 

 respiratory products, and including experiments on submaintenance 

 rations, have proposed" a somewhat sini])ler method ol computation for 

 attaining the same end. 



Thus far, the two sets of values substantially parallel each other. 

 It is in the method of expressing them for practical use in computing 

 rations that the two systems diverge. The writers have expressed them 

 directly in terms of energy ("Net energy values"), simply using a large 

 unit (the therm = 1000 kilogram calories) to avoid the inconvenience of 

 large numbers. Kellner, on the contrary, in view of the unfamiliar 

 nature of energy units and of the large numbers required to express 

 the energy values in terms of calories, was led to adopt as a substitute 

 the equivalent amount of digested starch. Suppose, for example, that 

 a sample of maize meal is found, either by direct experiment or by 

 calculation, to have a net energy value of 85,200 calories per hundred 

 pounds, or 85-2 therme, i.e. to be capable of contributing this amount 

 to the upkeep of the body. According to Kellner's investigations, one 

 pound of digestible starch has a net energy value of 1-071 therms. The 

 85-2 therms contained in one hundred pounds of maize meal might, then, 

 be supplied by 85-2 -;- 1-071 = 79-5 pounds of digestible starch and the 

 latter number is the "Starch value," in Kellner's sense, of the maize 

 meal. In other words, so tar as the energy supply to the animal is con- 

 cerned one hundred pounds of the maize meal might be replaced by 

 79-5 pounds of digestible starch, while conversely the starch value 

 midtiplied by 1-071 gives the net energy value in therms. 



Kellner's starch value may be said to be a mixed unit. It attempts 

 to express what are really quantities of energy in terms of matter and it 

 has always seemed to us an unfortunate and an unnecessary concession 

 to established usage. Moreover, experience has shown that in its actual 



1 Compare Kellner, The Scientific Feeding of Farm Animals (Goodwin's translation), 

 and Armsby, The Nutrition of Farm Animals, pp. 668-672. 



2 Journ. Agr. Researcli. 3 {190.')), 486; The Nutrition of Farm Animals, pp. 673-67.5. 



