MAMMARY GLAND SECRETION OF MILK. 547 



both possess, however, a larger proportion of casein, which forms a peculiarly 

 dense curd ; and the milk of the Goat is tainted with the peculiar odour of the 

 animal, which is more intense if the individual be dark-coloured. The milk 

 of the Cow will usually answer very well for the food of the infant ; care being 

 taken to dilute it properly, according to the age of the child. 



689. The change which naturally takes place, from the condition of Colos- 

 trum to that of true Milk, during the first week of lactation, is a very im- 

 portant one. The Colostrum has a purgative effect upon the child, which is 

 very useful in clearing its bowels of the meconium that loads them at birth ; 

 and thus the necessity of any other purgative is generally superseded. Occa- 

 sionally, however, the coloslric character is retained by the milk, during an 

 abnormally long period ; and the health of the infant is then severely affected. 

 It is important to know that this may occur, even though the milk may pre- 

 sent all the usual appearance of the healthy secretion ; but the microscope 

 at once detects the difference.* The return to the character of the early 

 milk, which has been stated to take place after the expiration of about twelve 

 months, seems to indicate that Nature designs the secretion no longer to be 

 encouraged. The mother's milk cannot then be so nutritious to the child as 

 other food;t and every medical man is familiar with the injurious conse- 

 quences, to which she renders herself liable by unduly prolonging lactation.^ 



690. From what has been stated of the close correspondence between the 

 elements of the Blood and those of the Milk, it is evident that we can scarcely 

 expect to trace the existence of the latter, as such, in the circulating fluid. 

 To what degree the change, in which their elaboration consists, is accom- 

 plished in the Mammary gland, or during the course of the circulation, there 

 is no certain means of ascertaining. The recent discovery of the usual pre- 

 sence of the organic compound named kiestine (which is nearly related to 

 casein), in the urine of pregnant women, seems to indicate that the conver- 

 sion of albumen into casein takes place in the blood, this curious excretion 

 being the means of preventing its accumulation in the circulating fluid, pre- 

 viously to the time when it is secreted by the mammae. It is evident that 

 this secretion cannot serve as the channel for the deportation of any element, 

 the accumulation of which would be injurious to the system ; since it does not 

 occur in the male at all ; and in the female at particular times only. Yet 

 there is reason to believe that if, whilst the process is going on, it be suddenly 

 checked, the retention of the material in the blood, or the re-absorption of the 

 secreted fluid, is attended with injurious consequences. Thus if, when the 

 milk is first secreted, the child be not put to the breast, an accumulation takes 

 place, which, if not relieved, occasions great general disturbance of the system. 

 The narrowness of the orifices of the milk-tubes obstructs the spontaneous 

 exit of the fluid, especially in primiparss ; the reservoirs and ducts become 

 loaded ; further secretion is prevented ; and a state of congestion of the ves- 

 sels of the gland, tending to inflammation, is induced. The accompanying 

 fever is partly due, no doubt, to the local disturbance ; but in part, also, there 

 seems reason to believe, to the re-absorption of the milk into the blood ; this 

 cannot but be injurious, since, although but little altered, the constitution of 

 milk is essentially different, especially in regard to the quantity of crystal liz- 



* See Donne, " Du Lait, et en particulier celui des Nourrices ;" and Brit, and For. 

 Med. Review, vol. vi. p. 181. 



f On the whole subject of Infant Nutrition, the Author would strongly recommend the 

 excellent little work of Dr. A. Combe, formerly referred to. 



$ One of these, which has particularly fallen under the Author's notice, is debility of 

 the retina, sometimes proceeding to complete amaurosis; this, if treated in time, is most 

 commonly relieved by discontinuance of lactation, generous diet, and quinine. 



See Dr. Golding Bird, in Guy's Hosp. Rep., vol. v. 



