332 SECRETION. 



are also increased, and the milk retains all of its qualities as a nutritive 

 fluid. 



Alcohol, especially when largely diluted, as in malt-liquors and other mild 

 beverages, is well known to exert an influence upon the secretion of milk. 

 Drinks of this kind almost always temporarily increase the activity of the se- 

 cretion, and sometimes they produce a certain effect upon the child ; but di- 

 rect and accurate observations on the actual passage of alcohol into the milk 

 are wanting. During lactation the moderate use of drinks containing a 

 small proportion of alcohol is frequently beneficial, particularly in assisting 

 the mother to sustain the unusual drain upon the system. There are, how- 

 ever, few instances of normal lactation in which their use is absolutely ne- 

 cessary. 



It is well known that the secretion of milk may be profoundly affected 

 by violent mental emotions. This is the case in many other secretions, as the 

 saliva and the gastric juice. It is hardly necessary, however, to cite many 

 instances of modification or arrest of the secretion from this cause, which are 

 quoted by authors. Yernois and Becquerel reported a case, in which a 

 hospital wet-nurse, who lost her only child from pneumonic fever, became 

 violently affected with grief and presented, as a consequence, an immediate 

 diminution in the quantity of her milk, with a great reduction in the propor- 

 tion of salts, sugar and butter. In this case the proportion of caseine was 

 increased. Astley Cooper reported two cases in which the secretion of milk 

 was instantaneously and permanently arrested by terror. These cases are 

 types of many others, which have been cited by writers, of the effects of 

 mental emotions upon secretion. 



Direct observations upon the influence of the nerves upon the mammary 

 glands are few and unsatisfactory. The operation of dividing the nerves 

 distributed to these glands, which has occasionally been practised upon ani- 

 mals in lactation, has not been observed to produce any sensible diminution 

 in the quantity of the secretion. It is difficult, however, to operate upon all 

 the nerves distributed to these organs. There are no observations indicating 

 the situation of a nerve-centre presiding over the secretion of milk, although 

 such a centre may exist. 



Quantity of Milk. It is difficult to form a reliable estimate of the aver- 

 age quantity of milk secreted by the human female in the twenty-four hours. 

 The quantity undoubtedly varies very much in different persons ; some women 

 being able to nourish two children, while others, though apparently in per- 

 fect health, furnish hardly enough food for one. Astley Cooper, as the result 

 of direct observation, stated that the quantity that can be drawn from a full 

 breast is usually about two fluidounces (60 grammes). This may be assumed 

 to be about the quantity contained in the lactiferous ducts when they are 

 moderately distended. Lehmann, taking for the basis of his calculations the 

 observations of Lamperierre, who found, as the result of sixty-seven experi- 

 ments, that between 1-7 and 2 ounces (50 and 60 grammes) of milk were 

 secreted in two hours, estimated that the average quantity discharged in 

 twenty-four hours is about 44'5 fiuidounces (1,320 grammes). Taking into 



