200 AGRICULTURAL EXPERIMENT STATION. 



It appears that method A, gives uniformly much lower results 

 than either of the other three methods, method C, giving the highest. 

 The average coefficients obtained by the four methods in 15 of the 

 19 trials, excluding the experiments where oat straw alone, and oat 

 straw with potatoes were fed, are as follows : 

 Method A. 56.9 per cent. 



" B. 67.3—10.4 above A. 



C. 72.2—15.3 " " 



" D. 67.5—10.6 " " 



The increase in coefficients of digestibility due to the corrections 

 applied, range in the 15 experiments from 6 per cent to 14.9 per 

 cent with method B, and from 10.5 per cent to 20.2 per cent with 

 method C. In those experiments where the dailj' ration was only 

 350 grains of oat straw, or 350 grains of oat straw and 1000 grains 

 of raw potatoes, the amount of nitrogen extracted as presumable 

 stoffivechselprodncte is relatively much larger, and in these instances 

 the coefficients by method B, are from 19.5 per cent to 30.2 per 

 cent, and by method C, from 33.6 per cent to 40.9 per cent larger 

 than by method A. 



The large differences in the results b}' the three methods in these 

 two experiments are due to the fact that in one case an abnormally 

 small amount was fed of a food poor iu nitrogenous material, and 

 that in the other, the amount of material added to the oat straw 

 contained a relatively large quantity of digestible substance as 

 compared to the additional protein consumed. 



The amount of waste nitrogenous products in the feces, such as 

 biliary compounds, etc., seems to be determined by the "wear and 

 tear" of the digestive apparatus, and not by the quantity of nitrogen 

 in the food. 



This "wear and tear" within a given time is proportionate, we 

 may believe, to the amount of food digested. The next table shows 

 that the nitrogenous material extracted from the feces by method B, 

 bears a more nearly fixed relation to the material digested than to 

 the protein fed. 



The error involved in method A, is in general, inversely to the 

 amount of nitrogen in the food. The corrections of methods B and 

 C then, affect the coefficients for oat straw and timothy much more 

 than that for clover ha v. 



