978 OF GENERATION LACTATION. 



quantity of Sugar, on the contrary, is at its maximum at first, and gradu- 

 ally diminishes. The amount of Butter (as appears from the wide ex- 

 tremes shown in the above tables) is more variable than that of any other 

 constituent. That some of the variations, moreover, are due to the char- 

 acter of the ingesta, and others to the external temperature, amount 

 of exercise, and other circumstances affecting the individual, is proved 

 by the inquiries of Dr. Playfair upon the Milk of the Cow. He has shown 

 that the amount of butter depends iu part upon the quantity of oily 

 matter in the food, and in part upon the amount of exercise which the ani- 

 mal takes and the warmth of the atmosphere in Avhich it is kept: exercise 

 and cold by increasing the respiration, eliminate part of the oily matter in 

 the form of carbonic acid and water; whilst rest and warmth, by diminish- 

 ing this drain, favor its passage into the milk. The proportion of Casein, 

 on the other hand, is increased by exercise. Dr. Playfair's experience on 

 this head seems to correspond with the results of common observation in 

 Switzerland ; for where the cattle pasture in very exposed situations, and 

 are obliged to use a great deal of muscular exertion, the quantity of butter 

 yielded by them is very small, whilst the cheese is in unusually large pro- 

 portion ; but these same cattle, when stall-fed, give a large quantity of butter 

 and very little cheese. It is quite possible, moreover, that particular breeds 

 of cattle may yield milk of a richer quality than others. Thus Vernois and 

 Becquerel 1 found that Tyrolese, Dutch, and Swiss cows give milk contain- 

 ing from 7 to nearly 10 per cent, of butter, with much casein and albumen; 

 whilst the cows in the immediate neighborhood of Paris furnished a poor 

 milk, containing only 3.6 or 3.7 per cent, of butter, and little casein. The 

 total amount of solid matter in the milk diminishes with age, being most 

 abundant in nursing women of from 15 to 20 years, and smallest in those of 

 from 35 to 40 years of age. 



815. 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. 

 Occasionally, however, the colostric 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 present all the usual appearances of the healthy secretion ; but the 

 microscope at once detects the difference. 2 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 ; 3 and every medical man is familiar with the inju- 

 rious consequences to which she renders herself liable, by unduly prolonging 

 lactation. 4 Cases are not uufrequent, however, in which the secretion con- 

 tinues as long as there is a demand for it ; and sometimes quite independently 

 of this. It is the habit among some nations, to suckle the children until 

 they are three or four years old, and to continue doing so even though another 



1 L'Union Medicale, xi, No. 26. 



2 See Donne, Du Lait, et en particulier celur des Nourrices, and Brit, and For. 

 Med. Review, vol. vi, p 181. 



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

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



4 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. 



