QUANTITY OF MILK 295 



fected by violent mental emotions. This is the case in respect to many 

 other secretions, as the saliva and the gastric juice. It is hardly neces- 

 sary, however, to cite many of the instances of modification or arrest of 

 the secretion from this cause that are quoted by authors. Vernois and 

 Becquerel reported a case in which a hospital wetnurse, 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 proportion of salts, sugar and 

 butter. In this case the proportion of casein was increased. Astley 

 Cooper reported two cases in which the secretion of milk was instanta- 

 neously and permanently arrested by terror. These cases are types of 

 many others, cited by writers, of the influence of mental emotions on 

 secretion. 



Direct observations on the influence of spinal nerves on the mam- 

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

 nerves distributed to these glands, which has occasionally been practised 

 on animals in lactation, has not been observed to produce any sensible 

 diminution in the quantity of the secretion. It is difficult, however, to 

 operate on 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 

 average 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 perfect health, furnish hardly enough food for 

 one. The quantity that can be drawn from a full breast usually is 

 about two fluidounces (60 grams). This may be assumed to be about 

 the quantity contained in the lactiferous ducts when they are moderately 

 distended. Taking into consideration the variations in the quantity of 

 milk secreted by different women, it may be assumed that the daily pro- 

 duction is between two and three pints (950 and 1420 grams). 



Certain conditions of the female are capable of materially influenc- 

 ing the quantity of milk secreted. It is evident that the secretion 

 usually is 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 becomes re- 

 established during lactation, the milk usually is diminished in quantity 

 during the periods, but sometimes it is not affected, either in its quantity 

 or composition. Should the female become pregnant, there commonly 

 is a great diminution in the quantity of milk, and that which is secreted 

 is regarded ordinarily as possessing little nutritive value. In obedi- 



