M. Meynet, in a remarkable report upon condensed milk, has raised a question which it is important to have solved in the interests of infants. This is my excuse for presenting to the French Society of Hygiene certain observations on this subject.

Is woman's milk richer in fatty matters and sugar in proportion to the caseine than that of the cow? Is the affirmative, sustained by a large number of chemists, a mistake that ought to be corrected?

Such is the question that needs to be answered.

In my last work on milk, my aim was to report new experiments, and hence I gave only the analysis of M. Colawell. By the side of the essays of MM. Doyère, Millon, Commaille, and Wurtz, I put those of Liebig, and quoted an interesting chapter written on this question by M. Caulier, in Dechambre's Encyclopedic Dictionary. These are the authorities upon which to base any opposition to the analyses of Boussingault, Regnault, Littre, and Simon, savants of no less renown.

The differences are easily explained.

Woman's milk is rarely to be had in sufficient abundance to make a complete analysis of it. In the country especially a few precious drops, obtained with difficulty, are carried off in a thimble to be placed under a microscope, where the number of fat globules are counted, and it is examined to see if they are not mixed with globules of colostrum.

It will be necessary at the outset to know whether the analyses given refer to milk drawn from the breast before nursing, or at the end. In the former case there will be an excess of caseine, in the second an excess of fat present. This is the reason that in nursing infants the intervals should not be too long, or the child will not be able to empty the breast completely, and it will obtain a milk too rich in caseine, too poor in butter, and one that it cannot digest.

This is the first proof of the importance of fatty matters for the alimentation of babes.

Let us turn to the second.

At birth, when the milk is still in a state of colostrum, the fluid contains a variable quantity of albumen coagulable by heat, much less caseine, and an excess of butter and sugar.

Cow's milk, immediately after calving, contains more butter and less caseine than milk produced some time later, when the specific character of ruminants begins to appear in the calf, that is to say, when it commences to graze the milk coagulates in the stomach. As in other mammals, an excess of fat helps digestion by subdividing the caseine and emulsifying it. But the milk of an animal recently calved is reserved for its young, and it is not until the time of weaning that the lacteal fluid is offered for human consumption.

Thus it is that the nursling of a day receives milk many months old and heavily loaded with caseine. This milk it cannot digest because the emulsifying element, the fat, is not present in it in sufficient quantity in proportion to the coagulable matter. We must not forget either that the difference in coagulation holds also with respect to difference in the age and in the kind of animal. Just so the rennet of a sucking calf has a greater power of coagulating cow's milk than that of a sheep, and vice versa.

"Clinical observation," says Dr. Condereau, "shows that all young infants digest human milk very easily and cow's milk very imperfectly. When it is fed on the latter, in the excreta will be found numerous fragments, sometimes very bulky, of undigested caseine. In most cases this caseine suffers more or less decomposition in the alimentary canal, which gives to the feces a tainted odor recalling that of putrid Roquefort cheese.

"The excrement vary in appearance as much as they do in odor. Frequently the caseous clots are not to be seen, and the stool has a clammy look reminding one of glazier's putty, while the color varies from dirty white to pale grayish yellow. That is due to the fact that the composition of the milk from different animals is far from being constant.

"The proportions of albumen to those of caseine are especially varied. For woman's milk the proportions are as 100 to 122.72. In goat's milk the proportions are 100 to 173.09. In cow's milk it is as 100 to 289.20.

"The conclusion is this: Caseine is not a food at all for the new born during a space of time, the duration of which is to be determined experimentally.

"This substance is a harmful burden that interferes with the regular action of the digestive organs. It is a premature food, and the more abundant the more injurious.

"Albumen on the contrary remains fluid in the presence of the gastric juice; it is separated from the other aliments by coagulation of the caseine. It is absorbed entire either in its natural state or in form of peptone."

According to clinical observation, it is still the fats that give to milk its hygienic value, and the excess of caseine is an obstacle to its digestion.

However, if cow's milk is not easily digested by children, experience proves that there are other kinds of milk, from other animals, which young stomachs are able to bear more easily. There are many proofs of this fact.

M. Tarnier, speaking before the Academy of Medicine on the artificial nourishment of the new born, reports that the milk of cows and goats, pure or diluted in different ways, that of condensed milk and Biedert's cream, have always given disastrous results at the Maternite in Paris, but that the mortality of the new born was considerably reduced from the day when ass's milk was introduced as food.

Ass's milk was given pure for six weeks or two months; then cow's milk diluted with one-half water until six months old, followed by pure cow's milk. This is the most rational course of artificial feeding.

Prof. Parrot reports analogous results obtained at the nursery opened at the Hospice des Enfants Assistes. By the aid of ass's milk he saved a number of the little syphilitics.

The following are the numerical results: 86 infants with hereditary taint of syphilis have been at the nursery. Of 6 fed exclusively on cow's milk, only 1 survived and the other 5 died. Forty-two were suckled by goats, of which 8 lived, 34 are dead, which is equal to a mortality of 80.9 per cent. Thirty-eight were suckled by an ass, of which 28 lived and 10 died; a mortality of 26.3 per cent.

Certainly these figures prove eloquently enough what chemical analysis shows, that ass's milk, being better borne by the infant's stomach, ought to have a composition resembling that of woman's milk. This analogy is not found to consist in the quantity of fat, but in the small amounts of dry residue (total solids) and of caseine.

Let us now examine the objections raised by M. Meynet.

Food has a considerable influence upon the composition of milk; this fact, stated by M. Riche in his treatise on chemistry, seem to be accepted by all.

The milk of carnivorae is excessively rich in caseine; that of herbivorae much less.

The food of woman, who enjoys a mixed alimentation, ought to have a composition intermediate between these two, and consequently ought to contain more caseine than that of the plant eaters. This is the logical deduction.

At first this reasoning misleads one, but numerous objections present themselves.

The food, no doubt, has some influence upon the composition of the milk of animals of the same species, but every animal can secrete something independent of any food, just as one kind secretes musk, another castor, etc. Yet it would not be an anomaly if an excess of caseine in proportion to the other substances was a true characteristic of ruminants.

But we admit that the milk of all mammals ought to have identically the same composition if their food suffered no modifications.

What is the food of ruminants? Without doubt it is essentially vegetable, and the plants of the field constitute the element par excellence of their nurture. These plants contain a large excess of carbohydrates in proportion to the nitrogenous.

But what are these other substances? What role do they play in digestion?

They are composed in great part of fibers and cells that suffer no change in the animal economy, and which are not acted upon by the gastric juice, as proved by their occurrence in excreta. The carbon is found almost unchanged, so that the excrements of herbivoiae, when dried, form a valuable fuel. Ruminants are compelled, in order to obtain nourishment from the plants that they eat, to extract their juices by repeated pressure (as in chewing the cud); and what do these soluble juices contain? Some saccharine substances, a little fat, but mostly albumen and vegetable caseine, that is to say, the substance which predominates in their lacteal secretions.

What, on the contrary, is the food of woman?

No doubt she gains much strength from the lean, muscular flesh that she eats, but besides this she has butter, oil, fats of all kinds, sugar, starches, and alcoholic beverages, all of which are favorable to the production of butter in the milk. Hence, aside from her physical constitution, the food of woman alone explains the relative excess of non-nitrogeneous substances.

Nitrogenous articles of food are expensive, while the other forms of nutriment are to be had in the form of potatoes, beans, and bread, products sold at a reasonable price. Yet logic demands that there shall be an excess of butter in proportion to caseine in the milk.

The discrepancies in analyses of woman's milk are easily explained by the mobile and impressible character of woman.

If bad treatment and bee stings are able to modify the composition of cow's milk, how much more ought the emotions of all sorts, which disturb the heart and head of woman, to change the composition of her milk?

But if new analyses seem to be needed, they ought to be made. This question is too important to rest in suspense. The mean composition of human milk for the first two months after delivery ought to be established. In chemistry, as in mathematics, figures alone are convincing. But from what has been said it is logical to conclude that an excess of caseine in milk is unfavorable to good digestion, while an excess of butter is favorable to it.--Translated from Journal d'Hygiene, March 1, 1883.