28 Milk and Its Products. 
although when cows lie still there is a larger per- 
centage of water and a correspondingly less _per- 
centage of solids in the milk. The difference in 
the milk drawn at morning and evening is due to 
the unequal time that elapses between the periods. 
In general the milk is richest in fat that is drawn 
after the shortest period, and this has been shown 
to be the case where cows have been milked three 
or four and even five times per day. It is, 
however, not an invariable rule that the milk is 
richest succeeding the shortest period. Not infre- 
quently it has been found that the milk is richer 
after the longer period. In a series of observa- 
tions made by the writer upon 12 cows, ex- 
tending over 221 days, in 72 cases the percentage 
of fat was greater in the morning; in 114 cases 
it was greater in the evening, and in 35. cases 
there was a difference of .1 of 1 per cent or less 
between the morning and the evening milk. In this 
instance the period from evening to morning was 
about two hours longer. The amount of variation 
that may oceur between the morning and evening milk 
is often very considerable. In the great majority 
of cases it is not more than .5 of 1 per cent, 
but variations so great as 2 or 2.5 per cent be- 
tween the milk of one morning and that of the 
preceding or following evening have frequently 
been noticed. It is probable that a part of this 
variation may be explained by the action of the 
lymphatics of the udder in reabsorbing a part of 
the fat when the milk remains for a long time 
in the vessels of ie? wal{igeso®® 
