STUDIES IN MILK SECRETION. 



By J. HAMMOND, M.A., and J. C. HAWK, B.A. 



{School of Agriculture, Cambridge.) 



II. THE RELATION OF THE GLANDS OF INTERNAL 

 SECRETION TO MILK PRODUCTION. 



Inteoduction. 



It is now generally recognized that the glands of internal secretion 

 play an important part in regulating metabolism and so controlling 

 the nutrition of the animal. Hatui^ found that castration was followed 

 by a putting on of fat except in those cases in which the pituitary under- 

 went a compensatory hypertrophy, when the animal remained normal 

 in weight. 



It seems possible that what is known as "individuality" in the 

 fatness or thinness of any animal or breed of animals is an expression 

 of the equilibrium between the various glands of internal secretion in 

 the body. This may also apply to "individuality" in the yield of milk 

 o£ cows. Injection of extracts of various glands of internal secretion 

 has in some cases a marked effect on milk secretion. Ott and Scott^ 

 have drawn up the following table, classifying the glands according 

 to the mode of action of their extracts on milk secretion. 



Exciting Inhibitory Synergistic 



Pituitaiy extract Adrenalin Orchitic extract 



Corpus luteum extract lodothyrin — 



Pineal gland extract Ovary minus corpus luteum extract — 



Thymus extract Spleen extract — 



Mammary gland extract Pancreas extract — 



Experiments have been performed with pituitary extract and with 

 adrenalin, and some of the results are described below. No attempt 



1 Jour. Ex]}. Zool. Vol. xv, 1913. - Therapeutic Gazette, p. 761, Nov. 1912. 



