CAUSES WHICH INFLUENCE THE MILK.

539

gradual increase of the casein, by which the main element of the infant's sustenance is made to bear a constant proportion to the demands of its daily growth.*

The same course of conduct would be proper in the case of women whose milk is of so poor a quality that their infants do not thrive upon it, since, though its deficiency in casein may render it unfit for the permanent support of the child, yet that circumstance will not prove prejudicial to it during the first few weeks of its

existence.

Unfortunately we are not possessed of any ready means by which we can determine, in the majority of instances, that a woman's milk is ill suited for the nourishment of her child; and, in practice, the infant's not thriving is often the first indication that we have of the propriety of a change. Certain qualities, indeed, which healthy milk ought to have, are readily ascertainable. Thus, for instance, it should have a specific gravity of about 1032, and an alkaline reaction; and, after the first month, should be free from colostrum corpuscles; while the oil-globules, which should be present in great number, ought to be of tolerably equal size, and each distinct from the other. In spite of presenting all these characters, however, the milk may have undergone very important changes, though of a kind which dexterous chemical analysis will alone discover. An increase in the quantity of the fatty matters in the milk seems, according to the observations of M. Becquerel, to be an almost constant attendant upon all diseases, whether acute or chronic, syphilis and far-advanced phthisis alone excepted; while acute diseases are attended by a notable increase, and chronic ailments by a still more remarkable diminution of the casein. Such changes in its composition cannot but modify very greatly its suitability as an aliment for the child; while the difficulty of ascertaining the existence of any of these alterations may at least teach us that the apparently healthy character of the milk is but a very imperfect guarantee of its real excellence.

*Though I have allowed the above paragraph to stand unaltered in this edition, yet it must be observed that the elaborate researches of MM. Vernois and Becquerel do not altogether bear out its accuracy. They deny, on the strength of twenty-six observations on the milk of different women within a fortnight after delivery, that any such excess of sugar, and feeble proportion of casein, then characterise it, as is stated above, on the authority of the late Professor Simon, of Berlin. They admit the existence of a larger quantity of butter, which, however, continues only so long as the colostrum corpuscles are still present. It is, however, much to be regretted that they did not institute a series of comparative observations, with reference to this point, on the milk of the cow, since the question involved in the accuracy of one or the other of the opposing statements is of very great practical importance.

540

SUBSTITUTES FOR THE MOTHER'S MILK.

Still, even though the difficulties of a complete analysis of the milk will generally render the attempt to make it impracticable, and though conclusions drawn from a partial examination will almost certainly be erroneous, there are, fortunately, some general rules fairly deducible from chemical analysis and clinical observation combined, which will generally suffice to guide us aright in the choice of a person to undertake the duties of wet-nurse to an infant whose mother, either from necessity or choice, fails to perform the duty of suckling it herself. The apparently good health of the woman and her child is of all evidence the most conclusive in favour of her fitness; but M. Becquerel found the nearest approach to a perfectly physiological state of the milk, in women from 20 to 25 years old, multiparæ, of strong constitution, previously well-nourished, brunettes, with small mammæ but an abundant secretion of milk, from three to five months after delivery, and in whom the menstrual discharge was suspended.

The question, however, which we often have to answer, and to answer, too, sometimes very soon after the infant's birth, is not as to the goodness of a wet-nurse, but as to the best substitute for the mother's milk. Now it is obvious that the more nearly the substitute we select approaches to the character of the mother's milk, the greater will be the prospect of the attempt to rear the infant upon it proving successful. Discarding, therefore, all those preparations of arrow-root, flour, or biscuit-powder, in which the vulgar repose such confidence, we shall not need any laboured argument to convince us that in the milk of some other animal we shall be likely to find the infant's most appropriate food. You will perceive, however, by the subjoined table, that there are many important differences between the milk of all the domestic animals and of the human female; both in the actual quantities of its constituents, and in their relative proportion to each other.

Table showing the composition of the Milk in Man and in

various Animals.*

COW'S MILK OCCASIONALLY UNHEALTHY.

541

The above table shows you that it is only in the milk of the ass that the solid constituents are arranged in the same order as in the human subject; casein preponderating in the milk of the cow and ewe, and butter in that of the goat. On this account, therefore, asses' milk is regarded, and with propriety, as the best substitute for the child's natural food. Unfortunately, however, expense is very frequently a bar to its employment, and compels us to have recourse to cows' milk, as being so much more readily procured. But though the cost may be a valid objection to the permanent employment of asses' milk, it is yet very desirable, when a young infant cannot have the breast, that it should be supplied with asses' milk for the first four or five weeks, until the first dangers of the experiment of bringing it up by hand have been surmounted. The deficiency of asses' milk in oily matter may, as has been suggested, be very much rectified by the addition to it of about a twentieth part of cream. The laxative property which it possesses is not so easily counteracted; and though Sir Henry Marsh's recommendation of heating it to 212° sometimes removes this quality, yet the experiment has not in my hands been by any means invariably successful. In such cases, however, the addition of about a fourth part of lime-water to the milk will generally suffice to control all tendency to diarrhoea.

*

When cows' milk is given, it must be borne in mind that it contains more casein than human milk, and less sugar; and that it is therefore necessary that it should be given in a diluted state, and slightly sweetened. The degree of dilution must vary according to the infant's age; at first, the milk may be mixed with an equal quantity of water, but as the child grows older the proportion of water may be reduced to one-third. Attention must be paid to the temperature of the food when given to the infant, which ought to be as nearly as possible the same as that of the mother's milk, namely, from 90° to 95° Fahrenheit; and in all cases in which care is needed, a thermometer should be employed, in order to ensure the food being always given at the same temperature. Human milk is alkaline; and even if kept for a considerable time it shows but little tendency to become sour. The milk of animals in perfect health likewise invariably presents an alkaline reaction, and that of cows when at grass forms no exception to this rule. Comparatively slight causes, however, exert a marked influence upon the milk of the cow in all respects; even in the most favourable circumstances, if the animal is shut up in a city and stall-fed,

* By Dr. Moore, of Dublin, in his paper already referred to.

542

QUANTITY OF FOOD PROPER FOR INFANTS.

all the solid constituents of its milk suffer a remarkable diminution; while the secretion further has a great tendency to become acid, or to undergo even more serious deterioration. There is evidently no occasion, then, to assume any intentional adulteration of the milk, in order to account for the symptoms of gastric and intestinal disorder so often produced by it in the case of children brought up in large towns. Whenever, therefore, the attempt is made to rear an infant by hand, in circumstances which render it impossible to obtain the milk of cows which are at pasture, it is desirable that the milk should be daily tested, and that any acidity should be neutralised by the addition of limewater, or of prepared chalk, in quantity just sufficient to impart to it a slightly alkaline reaction. If the bowels be disposed to be constipated, carbonate of magnesia may be substituted for the chalk. Unfortunately, there seem, as I stated a day or two ago, to be good reasons for believing that the milk of stall-fed cows often undergoes a deterioration much more serious than the merely becoming ascescent; and that changes not infrequently take place in it such as must render it wholly unfit for an infant's food, and calculated only to promote disease. The possibility of their occurrence shows the necessity, when an infant who is brought up by hand fails in health, for making a careful enquiry into the source of the milk with which it is fed; and for examining the fluid, if possible, both chemically and under the microscope, before proceeding to prescribe remedies for ailments which may be caused entirely by the unwholesome nature of its food.

The quantity of food proper to be given to an infant at one time, and the total amount which it may be supposed to require in the twenty-four hours, though questions of most obvious importance, have hitherto scarcely received any attempt at solution. The only observations bearing on the subject, with which I am acquainted, were made a few years ago by M. Guillot† at the Foundling Hospital in Paris. He weighed children both immediately before and immediately after suckling, and found that the increase of weight varied from about two to five ounces in children under a month old; and concludes that a thousand

* See the analysis of Vernois and Becquerel, op. cit. p. 131, and the results of Dr. Mayer's observations on cows in Berlin and its neighbourhood, in a valuable paper on the Artificial Feeding of Infants, in the first volume of the Verhandlungen der Gesellschaft für Geburtshülfe in Berlin, 8vo. p. 56, Berlin, 1846; and also two papers by Dr. Peddie in the London and Edinburgh Monthly Journal for 1848; and the observations of Dr. Klencke, of Leipsic, already referred to at p. 504.

↑ Journal für Kinderkrankheiten, July 1852, vol. xix. p. 113.

QUANTITY OF FOOD PROPER FOR INFANTS.

543

grammes, or about two pounds and a quarter avoirdupois, is the smallest quantity of milk that would suffice for the daily nourishment of a healthy infant during the first month of its existence. The number of children, however, on whom his observations were made, as well as the number of observations on each child, were both far too few to yield more than a very rough approximation to the truth with reference to this subject.

It may suffice for to-day, thus to have brought before you the main principles by which you must be guided in the attempt to rear a young infant by hand. Details as to the general dietetic management of infancy or childhood would not only carry us beyond the period allotted for this lecture, but would be a departure from our special object-of investigating the diseases of early life.