. 



Increasing Quantities of Fat in Diet on Metabolism in Dogs. 259 



the method of Kjeldahl, and the sulphates after the method of 

 Baumann. 



As far as the faeces were concerned, in all cases they were examined 

 with the ordinary precautions necessary in metabolism experiments, 

 each daily quantity being separately examined, and the periods sepa- 

 rated by means of charcoal. They were dried down over a water- 

 bath, after adding dilute sulphuric acid, so as to avoid any escape of 

 ammonia in the drying process. The drying was continued in a drying 

 cupboard until they became a constant weight, and from this the 

 quantity of water and solids was calculated. The dried residue was 

 analysed for nitrogen and fat after the usual methods. Naturally in 

 those cases where the fats were separately analysed, the portion of 

 faeces taken for the analysis was not dried down with the sulphuric 

 acid, but, on the other hand, extracted with alcohol, the alcohol extract 

 being evaporated over a water-bath, and the total extracted with ether, 

 and the fats, cholesterin, &c., separated, as I have already described in 

 a former paper.* 



As regards the carbohydrates, it was originally intended to estimate 

 the quantity in all the experiments, but it was found in one normal 

 dog, and in one dog in which the large intestine had been entirely 

 removed, that of the carbohydrates given in a diet of biscuit and meat 

 there was neither loss in the faeces in the normal, nor in the case of the 

 complete absence of the large intestine; it was therefore considered 

 unnecessary to repeat these experiments. 



In order to investigate the effect of the removal of the large 

 intestine on the general metabolism, it was necessary to examine in 

 close detail the normal conditions of dogs fed on, roughly speaking, 

 the same diet. 



The Influence of Increasing Quantities of Fat in tlie Diet on the Metabolism 



of Normal Dogs. 



For this purpose the quantity of proteid and carbohydrate through- 

 out each research was kept constant, only the quantity of fat being 

 increased during different periods, and the same experiments being 

 repeated on dogs with either the partial or complete removal of the 

 large intestine. In calculating the quantity of proteid or fat absorbed 

 from the alimentary canal, no allowance is made for the quantity of 

 nitrogen which is normally present in the faeces in a fasting animal. 



C. Voit and Fr. Miillerf have shown that even during fasting there 

 is an elimination of faeces. For example, in a dog of 30 kilos, the 

 average was about 2 grams of dried faeces daily, containing no less 

 than 0*15 gram of nitrogen. 



* Vaughan Harley, ' Eoy. Soc. Proc.,' vol. 61, 1897. 

 t Fr. Miiller, 'Zeit. f. Biol.,' vol. 20, p. 343, 1884. 



