Milk, an example of a natural "complete" food - That of the cow is its type - Its use as food almost universal - Essentially an animal food - Most important that it should be pure and uncontaminated - Being very susceptible of injury, in distribution and otherwise, and thus becomes a fertile source of disease - Many epidemics of fever, etc., caused by the milk trade - Tuberculous milk - Analysis, and nutritive value - Milk essentially food for the young growing animal - Whey - Koumiss - Strict sanitary measures employed to ensure the purity and wholesomeness of milk - Prudence requires it to be generally regarded as a raw product, to be taken only after boiling, especially by travellers abroad.

The term "complete," as we have seen in the fourth chapter, is employed to denote that the food so designated contains all the elements necessary to the support of the body, and to the activity of its functions. Most commonly, such nourishment is a compound of two or more animal or vegetable substances, combined in order to afford the various elements necessary to meet all the demands of animal life. But there is a notable example of a single animal product, perhaps the best which can be offered as a complete food; one prepared by nature, furnished in great abundance, and which we are all well acquainted with, namely, milk. It is a product which slightly varies in different species of the mammalian family. That form which we are most familiar with is the milk of the cow, and it may be taken as the type. It constitutes so large and so valuable a part of the food of man in temperate climates, that some account of it is desirable here, particularly as the subject is rapidly growing in interest and importance, and as the popular knowledge respecting it is very imperfect.

Milk is the type of a "complete" food provided by nature.

Importance of Pure Supply.

I have said that the subject of milk is growing in importance; this is true on the following grounds. First, because it is essential to the well-being of young children to have milk which is produced of excellent quality at its source; and secondly, it is equally necessary that it should not be adulterated, or otherwise injured in the processes of transit and distribution. Meantime, as our population grows more dense, sources of contamination increase, and the task of obtaining an absolutely pure supply is more difficult. Very much more is contained in these simple statements than is at first discerned by the popular eye.

Before making further comments thereupon, let us recall the fact that, excepting only the article of wheaten bread, milk is perhaps the most universally employed food in this country. And I am not quite sure that the exception made above is correctly stated to be so. Every man, woman, and child in the kingdom, with few exceptions, consumes milk in some form at least once or twice daily; while for the youngest part of the community, during the most critical stage of early growth, milk forms the chief and the best source of nourishment. Now it is to be remembered in connection with these striking facts, that milk is a complex animal food, and one which so rapidly decomposes, that in hot weather a few hours suffice to injure it materially. Moreover, it is extremely liable to contamination if exposed to impure atmospheric influences, etc. But the most serious danger connected with milk as food is associated with the vast daily process of distribution necessary in order to convey the product from the cow to the consumer. No doubt that water is wilfully added in some small quantity to a large proportion of the supply in order to cheapen it; but where this is not done, all the vessels employed in dairy operations are more or less carefully and completely washed twice a day. It is this contact with water, employed by no means always, as it ought to be, at the boiling point, which constitutes the milk trade a ready and unceasing agency for the spread of three or four forms of disease among the population. It is only within the last few years that we have become aware that one of the principal channels by which typhoid fever, scarlet fever, and diphtheria are propagated, is the agency which conveys the daily milk from the cow to every house in the kingdom. Water which contains some admixture of sewage matter is liable to become contaminated by the excreta of persons suffering from infectious disease; and thus, in its very employment for cleansing milk vessels, the seeds of disease may be deposited in a single milk can, from which twenty families, say, are supplied. It is foolish, or worse, to ignore the presence of this and similar sources of danger to the community, resulting from the rapid increase of population, or to affect that it is unwise to be sensitive concerning the presence of dangers to health in the daily routine of the household, seeing that their discovery and removal may render life there more enjoyable and secure.

Exceedingly important to ensure a pure supply, because every one is a daily consumer.

It decomposes rapidly, and is very liable to become tainted; to transmit the germs of disease, Had such counsel been listened to by our forefathers, the mortality from fever might still be in this country what it was forty years ago; moreover, we know that the cause now in question, like every other cause of fever, is a removable one, if reasonable precautions are taken. It was greatly due to the late Dr. Murchison, and to the late Mr. Ernest Hart, who more than any one studied this subject exhaustively, that the great epidemic of typhoid fever in the parish of Marylebone, in 1873, was traced to a single case at a country farm which supplied milk to a dairy in that parish; directly occasioning no less than two hundred and eighteen cases of fever among the customers of that dairy, of whom twenty-six died. From these a vast number of other cases arose, how many could never by any inquiry be correctly estimated by admixture with sewage matters.

Milk has largely disseminated typhoid.

A well-known illustration.

During the succeeding ten years no less than eighty-one (separate) epidemics were similarly traced in various parts of this country to milk distribution.*

There is another source of disease associated with the use of milk, besides the contamination described, arising from a constitutional malady to which the cow is subject, namely, tuberculosis. When this is present, the disease is liable to be communicated from a characteristic ulceration affecting the udder to the milk itself, rendering it highly dangerous to the consumer. So important is this fact, that I shall but quote the words of a high authority regarding the sole precaution which can render the consumer safe from infection, namely, "As regards milk, tuberculous infection is so readily destroyed by boiling that this ought to be done as a precautionary measure by every householder."+ Let me add that for many years, in travelling, whether in this country or abroad, I never take raw milk, but invariably pursue the course recommended at p. 212.

* See an admirable and very concise account of the subject in a paper read at a meeting of the Social Science Congress, at Huddersfield, October, 1883, by Mr. Ernest Hart, and entitled, "Is it desirable to take any, and what, further measures to prevent the spread of Zymotic Diseases through the Milk Supply of our Towns?" London : Smith, Elder & Co.

+"A System of Medicine," edited by J. Clifford Allbutt, M.A., M.D., etc. (Macmillan, 1897), vol. ii., article "Tuberculosis," by Sidney Martin, M.D., F.R.S., etc., Professor of Pathology in University College, London, etc.