230 SOUECE OF THE BUTTER OF MILK. 



carefully measured. The 7 cows furnished 17,576 quarts of milk; its 

 weight was 36,382 pounds. Being analyzed from time to time, it was 

 found to yield 3.7 per cent, of butter, completely deprived of water. 

 From this it follows that these 7 cows furnished during the year 1346 

 pounds of butter. 



During this time they ate 30 pounds of hay, clover, and grass each 

 day; that is to say, the 7 cows consumed during the year 77,650 Ibs. 



Now if in 100 pounds of hay there are 1.8 of fat, the 77,650 pounds 

 represent 1378 ; recollecting, however, the use of clover, which is richer 

 in fat, the amount should rise to more than 2000 pounds. But the but- 

 ter obtained was only 1346 pounds. 



From this experiment, therefore, we gather, that a cow which is giving 

 milk finds much more fat in the fodder she eats than is subsequently 

 yielded in her butter. We may therefore conclude that such an animal 

 extracts from her food most of the fat it contains, and that she either 

 stores it up in her adipose cells, uses it for the production of heat, or con- 

 verts it into butter. 



In the argument, as thus presented by M. Dumas, the question is con- 

 sidered in its quantitative aspect, no allowance being made, however, for 

 the amount of oily material accompanying the fasces, and no estimate of- 

 fered of the proportion destroyed for the sake of producing heat. It 

 might be that the entire amount of fat escapes in the former of these 

 ways, and that, though a sufficiency occurs in the food, it is not absorbed 

 therefrom into the system. 



There are many facts which show that the identical fat occurring in 

 The identical the food is actually delivered by the mammary gland with 

 [sfomid^i/the raan y f its quantities unchanged. Thus, if by chance cows 

 milk. should eat the tender shoots of pine-trees, or wild onions, or 



other strong-smelling herbs, the milk is at once contaminated with the 

 special flavor of their oils. The same, too, takes place when turnips are 

 introduced in their diet. If half the allowance of hay for a cow is re- 

 placed by an equivalent quantity of linseed-cake, rich in oil, the cow 

 maintains herself in good condition, but the milk produces a butter more 

 than usually soft, and tainted with a peculiar flavor derived from the lin- 

 seed oil. 



To the preceding facts it is unnecessary to add any observations in re- 

 lation to the carnivorous mammals, which obviously find in their prey 

 large quantities of 'fat. In the chapter on calorifacient digestion, and in 

 that on the functions of the liver, the evidence was presented both as 

 regards the reception of oily material from the food, and likewise its fabri- 

 Sufficient cation in the system. From these sources conjointly it may 

 of fat therefore be plainly seen that fats of various kinds must al- 



ways exist in the blood. A simple arithmetical computation, 



