86 SECRETION. 



querel mention a very striking case, in which a hospital 

 wet-nurse, who had lost her only child from pneumonia, 

 b.ecame violently affected with grief, and presented, as a con- 

 sequence, an immediate diminution in the quantity of her 

 milk, with a great reduction in the proportion of salts, sugar, 

 and butter. In this case the proportion of caseine was in- 

 creased. 1 Sir Astley Cooper mentions two cases in which 

 the secretion of milk was instantaneously and permanently 

 arrested from terror. 3 These cases are types of numerous 

 others, which have been reported by writers, of the effects 

 of mental emotions upon secretion. 



In the present state of oar knowledge, we can only com- 

 prehend the influence of mental emotions upon secretion, by 

 assuming that they operate through the nervous system ; and 

 in many of the glands, the influence of the nerves has been 

 clearly demonstrated by actual experiment. Direct observa- 

 tions, however, upon the influence of the nerves upon the 

 mammary glands are few and unsatisfactory. The opera- 

 tion of dividing the nerves distributed to these glands, 

 which has occasionally been practised upon animals in lac- 

 tation, has not been observed to produce any sensible dimi- 

 nution in the quantity of the secretion. 3 It is difficult, 

 however, to operate upon all the nerves distributed to these 

 organs. 



Quantity of Milk. It is very difficult to form a reliable 

 estimate of the average quantity of milk secreted by the hu- 

 man female in the twenty-four hours. The amount undoubt- 

 edly varies very much in different persons ; some women 

 being able to nourish two children, while others, though ap- 

 parently in perfect health, furnish hardly enough food for one. 



1 VERNOIS ET BECQUEREL, Du lait cJiez la femme dans Tctat de sante et dans 

 fetal de maladie, Paris, 1853, p. 73. 



2 COOPER, The Anatomy and Diseases of the Breast, Philadelphia, 1845, 

 p. 101. 



3 LONGET, Traite de physiologic, Paris, 1869, tome ii., p. 291. 



