146 Studies in Milk Secretion 



SUMMAEY AND CONCLUSIONS. 



I. As a result of withholding food for a few days, together with 

 an injection of phloridzin, thereby reducing the nutrition, the daily 

 yield of milk in goats was diminished and in one case the flow was 

 actually stopped. On giving food again the yield returned almost 

 to normal within a few days. 



II. As the daily yield of milk diminished under these conditions 

 so the percentage of fat in the milk rose. Limitation of the available 

 nutriment in the body (change from a high to low state of nutrition) 

 did not reduce the percentage of lactose or protein in the milk (Paton 

 and Cathcart^) but reduced the quantity of milk (together with the 

 amounts of protein, sugar and salts) produced. The secretion of fat 

 was not at first affected by the change in metabolism and as a conse- 

 quence milk rich in fat was produced. 



III. The amount of fat secreted per day under these conditions of 

 diminishing yield was however not constant but became reduced, 

 possibly as a secondary effect of the decreased secretion taking place 

 in the gland cells. 



IV. On again giving food to animals in such a reduced state of 

 nutrition, the percentage of fat in the milk decreased as the yield 

 increased, in some cases to such an extent that it was below that of 

 the normal milk before the experiment began. 



The experiments described above were performed at the Field 

 Laboratories, Cambridge, in connection with the School of Agriculture, 

 in 1913 and 1914; the expenses being defrayed by a grant ffom the 

 Board of Agriculture and Fisheries out of funds placed at their disposal 

 by the Development Commissioners. 



We are indebted to the Highland and Agricultural Society of 

 Scotland for the loan of block for reproducing Fig. 2. 



^ Jorir. of Physiol. Vol. XLii, 1911. 



{Received June 8lh, 1916. 



