FOODS. 79 



derived from German investigations ; * mucli information 

 has already been obtained upon this subject, though a 

 great deal yet remains to be accomplished. The general 

 method of investigation has been to supply an animal 

 with weighed quantities of food, the composition of which 

 has been ascertained by chemical analysis. During this 

 experimental diet the solid excrements are collected and 

 weighed, and are finally analysed by the same chemical 

 methods previously applied to the food. Subject, there- 

 fore, to certain small corrections for intestinal secretions, 

 we obtain by this plan the amount of each constituent of 

 the food which has passed through the animal unabsorbed, 

 and by difference the amount digested. The proportion 

 of each constituent digested for 100 supplied as food is 

 known as its " digestion coefficient." 



1. Experiments with Ruminants. — Ruminating animals 

 possess an extensive digesting apparatus, consisting of 

 the well-known four stomachs, in addition to the intestinal 

 organs. Food takes a considerable time in passing 

 through this system. In changing the diet of an ox five 

 days will generally elapse before the remains of the 

 preceding diet are expelled by the animal. Animals of 

 this class are specially adapted for the digestion of bulky 

 foods, containing much fibre. 



Experiments have been made with oxen, cows, sheep, and 

 goats. The power of these different animals for digesting 

 food is apparently very similar, but no accurate compari- 

 sons have as yet been made. The following table shows 



* The information given in this section is taken almost entirely from the 

 admirable work of Dr. E. Wolff, "Die Ernahrung der Landwirthschaftlichen 

 Nutzthiere," with its valuable Supplement just published. 



