THE SECRETION OF MILK.

King Country Chronicle, Volume VI, Issue 439, 14 February 1912, Page 3

THE SECRETION OF MILK.

The secretion of milk in the system of the cow seems to be similar in its nature to the composition of blood. A difference seems to be that the red corpuscles of the blood appear§ to be replaced by globules of fat, and this change probably takes place in the milk gland itaelf. We are in the habit of calling it a bag, but it really is not a bag, but a connection of minute vessels, which are engaged in selecting and converting the milk out of the material brought to it by the circulatory system. At the time, the tissues of the bag become charged with the milk as it is made, and stores it up ready for use. Under the ordinary conditions of a calf sucking a cow, the irritation produced by the action excites the gland to produce more liquid for use, but where the gland is only emptied twice a day, it acts as a storage vessel, and the same result occurs as when milk is placed ; n a vessel for the cream to rise. However, there is this difference: that whereas atfer the milk has left the bag it will take from 12 to 3(3 hours for the cream to rise, in a cow's bag it seems to separate at once. This is shown by the difference there always is between the milk first drawn from the cow and the last milk, the first milk drawn giving about 1.25 per cent, of butterfat, and the last milk giving about 7.75 per cent., ar.d the last of all, called the strappings, giving as much aB 10 per cent, of butterfat.