976 OF GENERATION LACTATION. 



Physiologically considered, 1 the most marked peculiarities of the colostrum 

 in the cow are the concentration of nutritive matter in it; the greater facility 

 with which it coagulates by rennet as compared with older milk, and its 

 greater power of resisting change when exposed to the action of air. All of 

 these are qualities which may be eminently serviceable, viewing it as the 

 first food of the young animal. Thus its easy coagulability may be adapted 

 to the comparatively weak gastric juice of the young animal. Its power of 

 remaining semifluid, and of resisting change may adapt a part of it to the 

 intestines, to promote the removal of the meconium ; whilst its concentration 

 as nutritive matter may permit it to fulfil the same office for the young mam- 

 mal as the food-yolk for the oviparous vertebrate. According to Bernard, 2 

 the Colostrum of the Human female contains a very large quantity of al- 

 bumen, since it coagulates en masse when it is heated. At a later period 

 none can be discovered by this method; but if sulphate of magnesia be 

 added, all the casein and the butter will be thrown down, and on filtration 

 will be left on the filter with the sulphate of magnesia; the filtrate will then 

 contain the albumen and the sugar of milk, and will coagulate on heat. All 

 the larger globules of oil may be removed by repeated filtration ; and the 

 fluid is then nearly transparent. This, in fact, is the simplest way of sepa- 

 rating the oleaginous from the other constituents of the milk; as but little 

 casein then adheres to the former. The transparent fluid, which has passed 

 through the filter, contains nearly the whole amount of the casein of the 

 milk ; but even in this fluid there are found globules too minute to be kept 

 back by the filter, whose chemical reactions mark them as oleaginous. 



813. We shall now consider the chemical characters of each of the fore- 

 going ingredients. The Oleaginom matter of milk principally consists of the 

 ordinary components of fat; but it also contains another substance peculiar 

 to it, designated as butyrin, to which the peculiar smell and taste of butter 

 are due; this yields in saponification three volatile acids, of strong animal 

 odor, to which Chevreul has given the names of butyric, caproic, and capric 

 acids. These peculiar acids are not only formed when the butyriu is treated 

 with alkalies ; but are produced by the ordinary decomposition of this princi- 

 ple, which is favored by time and moderate warmth. The Casein of Human 

 milk, however, by some chemists regarded as only a combination of albu- 

 men with soda, is usually said to be much less precipitable by acids than is 

 that of the Cow; very commonly resisting the action of the mineral acids, 

 and even that of the acetic; but being always coagulated by rennet, though 

 the curd is long in collecting. On this point, however, there has been much 

 discrepancy of statement, on which the experiments of Mr. Moore 3 throw 

 some light. It appears from the results obtained by him, that Human Milk 

 forms with most acids two sets of compounds, one of them soluble in water, 

 the other insoluble; the latter being formed only when the quantity of acid 

 is large in proportion to the casein. Thus, when two fluid ounce* of Cow's 

 rnilk were boiled with a single drop of nitric acid, complete coagulation of 

 the casein at once took place; but when two fluid drachms of Human milk 

 were treated in the same manner, no coagulation occurred, though the casein 

 was at once thrown down by a solution of ferrocyanide of potassium ; the same 

 quantity of milk, with five drops of the acid, formed a coagulum which was 

 not very manifest until after the lapse of five hours, but was very complete, 

 the serous fluid not being found to contain any casein by testing it with fer- 

 rocyanide of potassium; and it required ten drops of nitric acid to produce 



1 Physiological Researches, by J. Davy, M.D., F.R.S., 1863, p. 141. 



-' I. ''runs, vol. ii, 18-3!), p. 224. 



3 Dublin Quart. Juurn. of Med. Sci., vol. vii, p. 280. 



