FEEDING OF ANIMALS. 295 



several possible sources of error. He proposed that new ex- 

 periments with geese and with pigs should be made ; and, in 

 a subsequent conversation one of us had with him, he ex- 

 pressed his willingness to undertake a conclusive experiment 

 with pigs. 



Weiske and Wildt x did undertake an investigation with Experi- 

 pigs to determine the point. But one animal was fed on food 1 ^^ omA 

 so rich in nitrogen that it suffered in health, and the experi- Wildt. 

 ment had to be discontinued ; and the other on food so poor, 

 that it fattened extremely slowly, and hence, at the conclu- 

 sion, calculation showed that there was enough of the con- 

 sumed nitrogenous matter available for fat formation to cover 

 the whole of the fat which had been produced. 



Professor Emil von Wolff, in his work entitled Die Wolff's 

 rationelle FuUerung der landwirthschaftlichen Nutzthiere, auf views - 

 Grundlage der neueren Thier - physiologischen Forschungen, 

 published in 1874, assumed that albumin was probably the 

 exclusive source of the fat of the fattening herbivora of the 

 farm. But he made the reservation, that the amounts of 

 increase produced in relation to constituents consumed, which 

 common observation showed may be obtained with pigs, and 

 still more the results recorded of some direct experiments 

 with those animals (presumably our own), are almost incom- 

 prehensible without assuming the direct concurrence of the 

 carbohydrates in the formation of the fat. Nevertheless, he 

 considered that such evidence was inconclusive, and that 

 experiments with pigs should be made in a respiration appara- 

 tus to settle the question. 



After the inconclusive results of Weiske and Wildt, and Re-caicu- 

 the publication of Professor Wolff's views, as above quoted, ^^Sm- 

 we carefully reviewed and re-calculated many of the results of sted experi- 

 our feeding experiments, including some with oxen and with ments - 

 sheep as well as those with pigs, in order to satisfy ourselves 

 whether any doubt could be entertained of the views we had 

 previously advocated. 



The result of this examination, so far as the ruminants Source of 

 were concerned, was to show that, owing to the comparatively ^^J 

 small amount of increase obtained with them from a given 

 amount of constituents consumed, the quantity of nitrogenous 

 substance passed through the system for the production of a 

 given amount of increase was, in most cases, so large as to 

 admit of the assumption that the whole of the fat formed 

 might have had its source in transformed nitrogenous matter. 

 As will be seen further on, however, some of the experiments Source of 

 with sheep showed that, at any rate part of the fat stored up {fjfj™ 



1 Zeitschri/t fiir Biologie, Band 10. 



