FEEDING OF ANIMALS. 259 



more oats and straw, and so on. In each, case he noted the 

 change in weight, and in the condition of the animals in other 

 respects, if any; and he judged accordingly, whether the 

 amount of food given in substitution was too much or too 

 little, and whether, therefore, the practical or the theoretical 

 results were the most to be relied upon. 



He brought together in a table x the estimates of the value 

 compared with 100 of hay, of the 76 different articles of 

 food according to the amount of nitrogen he found in them ; 

 and side by side he gave the hay value of the foods according 

 to the published estimates of others, and to the results of his 

 own practical trials. 



Subsequently, however, Boussingault was not satisfied with Digestible 

 his results so obtained, and he pointed out that what was still ai lf t ^ 1 ' 

 wanting was the determination of the amount of the various nitrogenous 

 non-nitrogenous constituents also, and of how much of them a ^f ro no e ^ ous 

 was digestible, and how much indigestible ; and eventually substances 

 he determined in ninety different food-stuffs, not only the ™ foods. 

 nitrogen, but the mineral matter, the woody fibre or cellulose, 

 the fatty matter, and (probably by difference) the remaining 

 non-nitrogenous matters, which he recorded as starch, sugar, 

 and allied bodies. As to the nitrogen, he still, as formerly, 

 multiplied the amount found by 6.25 to represent albumin, 

 legumin, or casein. 



He also still took 100 parts of hay as the standard by which 

 to compare the nutritive value of other foods ; as, for rumin- 

 ants and horses, he considered it a good standard food, and 

 that the relation in it of the nitrogenous and the digestible 

 non-nitrogenous constituents was fairly normal. He now, 

 however, modified the meaning of the equivalent arrived at, 

 by taking into account the amount of digestible non-nitro- 

 genous substance associated with the standard amount of 

 nitrogen in each case ; and, if there were a deficiency, he 

 stated how much of some food rich in digestible non-nitro- 

 genous matters should be added to complete the equivalent, Equivalent 

 and so make it comparable with the 100 of hay. Indeed, he ratlons - 

 now laid it down that equivalent rations must contain equal 

 amounts of digestible non-nitrogenous a3 well as of the nitro- 

 genous bodies. 



In the case of the ninety descriptions of food which he 

 analysed as above referred to, he gave a table 2 recording the 

 results obtained, and then showed the amount of each food 

 required to contribute the same quantity of nitrogenous 

 substance as 100 of hay. Next, he calculated how much 

 nutritive non-nitrogenous matter, reckoned as carbohydrate 



1 Rural Economy, &c. English edition, 1845. H. Bailliere, London. 



2 Economie Burale, deuxieme edition, 1851, vol. ii. pp. 356-363. Paris. 



