THE MAINE EXPERIMENT STATION. 65 



small amounts of fat on the hardness of butter, and butter fat. 

 Eight different gluten meals were used, varying in fat content 

 from one per cent to nineteen per cent, also in other feeding 

 trials gluten feed, flax meal, and cottonseed meal. Eleven 

 cows were employed and twelve tests made. The feeding 

 periods were from two to four weeks each and extended over 

 three years. Results: The gluten meals with high fat con- 

 tent produced soft butter with fat of low melting point and 

 high iodine number. 



Gluten meals containing very small amounts of fat or oil, made 

 butters of about normal firmness. When tallow was added to 

 the ration, the hardness of the butter was somewhat increased. 

 Cottonseed meal produced a hard butter. The hardness of 

 butter can be regulated to a large extent by the food of the 

 cows. 



THE MINERAL INGREDIENTS OF MILK. 



Analyses were made of the ash of the milk, from six cows, 

 representing three breeds. Results: The differences in com- 

 position were great, even with cows of the same breed. The 

 potash and phosphoric acid were the most variable constituents. 



THE FAT GLOBULES OF MILK. 



The milk of five cows, representing three breeds, was exam- 

 ined and the relative size and number of the globules determined, 

 in both the whole and skimmed milk. Results: The globules 

 of the milk from the Jersey cows were much larger than in the 

 milk from the cows of the other breeds. In every case the 

 globules of the skimmed milk were less than one-half the size 

 of those from the whole milk. 



EFFECTS OF TUBERCULIN ON TUBERCULOUS COWS. 



The tests were applied to a herd of fourteen cows and cover 

 periods of from one to two years. Results: The tests together 

 with the autopsies indicate that tuberculin is a very delicate 

 agent for determining the presence of tuberculosis. It is very 

 doubtful if cows ever react under a properly made tuberculin 

 test unless they have tuberculosis. On the other hand, it is 

 very evident that cows sometimes have tuberculosis, or, at 

 least, tuberculosis growths in their bodies, and yet fail to react 

 under the tuberculin test. 



