LACTATION 597 



glands to increased activity in all directions, tending to the pro- 

 duction of a larger quantity of milk rich in all kinds of solid 

 constituents; whilst other substances may be looked upon as 

 stimulating the cells in a special manner, tending to the increased 

 production of certain only of the constituents of the milk." ^ 



According to Crowther's researches on cows, change from a 

 highly nitrogenous diet to one relatively poor in nitrogen causes 

 secretion, of a greater quantity of milk, but there is a decrease in 

 the fat content, this being more pronounced in the morning than 

 in the evening milk. A change in the reverse direction effected an 

 improvement in the quality of the milk. Concentrated food given 

 either in the morning or evening tended to increase the fat content 

 of the morning milk, but had little or no effect upon the evening 

 milk. These alterations were found to persist without appreciable 

 diminution for fully five weeks after the change of treatment. 



There are a number of preparations in the market, known as 

 galactogogues, which are said to increase the flow of milk in women, 

 but, according to Williams,, any virtue which they possess is due 

 largely to the quantity of fluid which is taken with them.^ It is 

 stated also that certain particular food-stuffs have a very appreciable 

 effect upon the quantity and quality of milk in cows. Thus bean- 

 meal is said to increase the flow of really good milk, unless it is 

 given in immoderate quantities. Brewers' and distillers' grains are 

 likewise described as having a beneficial influence upon the milk 

 supply, but if given too freely they tend to injure the breeding 

 capacity, and in consequence are most used in town dairies where 

 the cows are not bred from.^ Many substances ingested by the 

 mother pass unaltered into the milk. It is well known that certain 

 foods {e.g. turnips) cause an tmpleasant taste or smell in the milk 

 of cows to which they are supplied. Lehmann's experiment, in 

 which sodium sulphindigotate was injected into the veins of a 

 goat, and shortly afterwards made its appearance in the milk, has 

 already been referred to (p. 590). So also it has been found that 

 immunity from disease may be acquired by young animals being 

 suckled by a female which had previously become immune, the 

 antibody to the disease being absorbed in the ingested milk. 



It is generally recognised that the nature of the surroundings 

 has an influence over the mammary secretion. For example, the 



' Sharpey Schafer, loc. cit. There is evidence also that an abnormal diet 

 during and previous to pregnancy may arrest the normal mammary develop- 

 ment. See Watson (B. P.), "The Effect of a Meat Diet on Fertility and 

 Lactation," Proc. Roy. Soc. Edin., vol. xxvii., 1907. For general literature see 

 Meigs, "Milk Secretion as Related to Diet," Physiological Reviews, vol. ii., 1922. 



2 Williams (W.), Obstetrics, London, 1904. 



' Wallace (R.), Farm, Live Stock of Great Britain, 4th Edit., Edinburgh, 1907. 



