The careful inspection of the table for individuals shows plainly, 

 in the case of the four cows continuing through the experiment, 

 that volatile acids decrease and that the iodine number increases 

 as the period of lactation advances. These facts have been 

 noticed by so many observers that they may be regarded as fol- 

 lowing a natural law. The inspection also shows the variation in 

 both constituents of the butter from different cows when they are 

 fed upon the same rations. This is especially noticeable in the 

 last series of samples when the cows were at pasture. The vari- 

 ations are due, no doubt, both to peculiarities of breeds or indi- 

 viduals, and to the period of lactation. By referring to the de- 

 scription of the cows it will be seen that Duchess and Duchess, 2d, 

 were of the same breed and in nearly the same stage of lactation. 

 Duchess of Hanover and Chinchilla were also in nearly the same 

 period of lactation, but were of different breeds. 



The influence of breed may be left out in studying the effect of 

 the food, but the influence of the period of lactation must be care- 

 fully considered. 



It has already been mentioned that the rations in this series 

 contained the same quantities of hay and ensilage, but varied in 

 the kind and amount of grain. 



IN THE PREPARATORY PERIOD, 



as has also been mentioned, the ration (a) contained equal quantities 

 of each grain, and served to show the variations clue to breed and 

 period of lactation, and also as a starting point with which to com 

 pare the different rations. 



CORN MEAL AND GLUTEN MEAL 



were fed in rations (b) and (c) respectively, and were used with 

 groups I and II and with the different cows individually. Ration 

 (b) was fed to group I after (a), to group II after (c), and the indi- 

 viduals of the groups, Aurora, Clio, Duchess of H., and Frost, were 

 tested separately at the same time ; it was fed to Chinchilla, after 

 ration (e), the cotton-seed meal ration. In no case has it changed 

 the volatile acids from their natural decrease ; but in each case 

 the iodine number has been decreased, which is opposed to the natu- 

 ral progress of lactation and must be due to the food. 



