284 Dr. Lyon Play fair on the Milk of the Cow. 



last drawn from the udder contains much more cream than 

 that first obtained*. 



1st day. The cow, fed in the meadow upon after-grass 

 during the day, was driven home to the cow-house in the 

 evening. The milk then obtained amounted to four quarts. 

 A portion of this was subjected to analysis. 

 Specific gravity of milk, 1034". 



1 1 *1 28 grammes of milk gave — In 100 parts. 



11-128 100-0 

 During the day the cow had considerable exercise. Before 

 being milked, it had half a mile to walk from the meadow. 

 The nourishment in after-grass being small compared with 

 fresh grass, the animal had to eat a greater quantity than it 

 otherwise might have done, and consequently had to traverse 

 more ground in order to procure it. The exercise which it 

 thus received, by increasing the number of its respirations, 

 must have occasioned a greater supply of oxygen to the 

 system. This oxygen, as we shall afterwards show, unites 

 with the butter and consumes it; consequently less butter is 

 contained in the milk of the cow than would have been the 

 case had its pasture been rich grass. 



But, after being removed into the shed, less oxygen was 

 respired, and the warmth of the house was equivalent to a cer- 

 tain amount of unazotised foodf . The animal received nothing 

 to eat during the night, and therefore the milk of the morn- 

 ing must have been derived from the after-grass consumed 

 during the day. This milk measured four and a half quarts. 

 Specific gravity, 1032. 



15-280 100-0 

 * Schiibler says that the milk last drawn contains three times as much 



cream as that first procured. 



Dr. Anderson (Dickson's Practical Agriculture, vol. ii. p. 517) found the 



cream in the last cup of milk drawn from the udder, compared with that 



of the first cup, in the proportion of 16 to 1. 



f In this paper we take for granted that the leading features of Liebig's 



' Animal Physiology ' are acknowledged as true. 



