370 SECRETION. 



vations upon the human subject and the inferior animals, that, while the quantity of 

 milk is increased by taking a large amount of simple water, the solid constituents 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 secretion, and sometimes they pro- 

 duce a certain amount of effect upon the child ; but direct 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, particu- 

 larly in assisting the mother to sustain the unusual drain upon the system. There are. 

 however, few instances of normal lactation in which their use is absolutely necessary. 



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 the numerous instances of modifi- 

 cation or arrest of the secretion from this cause, which are quoted in many works. Ver- 

 nois and Becquerel mention a very striking case, in which a hospital wet-nurse, who had 

 lost her only child from pneumonia, 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 proportion of salts, sugar, and butter. In this case the proportion of 

 caseine was increased. Sir Astley Cooper mentions two cases in which the secretion of 

 milk was instantaneously and permanently arrested from terror. These cases are types 

 of numerous others, which have been reported by writers, of the effects of mental emo- 

 tions upon secretion. 



In the present state of our knowledge, we can comprehend the influence of men- 

 tal emotions upon secretion, only by assuming that they operate through the nervous 

 system ; and, in many of the glands, the influence of the nerves has been clearly demon- 

 strated by actual experiment. Direct observations, however, 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 quan- 

 tity of the secretion. 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 quan- 

 tity of milk secreted by the human female in the twenty -four hours. The amount un- 

 doubtedly varies very much in different persons ; some women being able to nourish two 

 children, while others, though apparently in perfect health, furnish hardly enough food 

 for one. Cooper, as the result of direct observation, states that the quantity that can be 

 drawn from a full breast is usually about two fluidounces. 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 Lampe'rierre, who 

 found, as the result of sixty-seven experiments, that from fifty to sixty grammes of milk 

 were secreted in two hours, estimates that the average quantity discharged in twenty- 

 four hours is 1,320 grammes, or about 44'5 fluidounces. Taking into consideration the 

 evident variations in the quantity of milk secreted by different women, it may be 

 assumed that the daily production is from two to three pints. 



Certain conditions of the female are capable of materially influencing the quantity of 

 milk secreted. It is evident that the secretion is usually somewhat increased within the 

 first few months of lactation, when the progressive development of the child demands an 

 increase in the quantity of nourishment. If the menstrual function become reestablished 

 during lactation, the milk is usually diminished in quantity during the periods, but some- 

 times it is not affected, either in its quantity or composition. Should the female become 

 pregnant, there is generally a great diminution in the quantity of milk, and that which 



