Bang: “Ueber die Aurscheidungs des Jodothyrius durch die Milch,” Berl. klin. Wochenschrift, Dec. 27, 1897. Footnote 291: C. R. de l’Académie de Medicine, 1898. Another fact, upon which we would like to insist, is that when we extirpate the thyroid gland of goats or other animals, their milk contains (as shown by Professor Lanz in the case of goats) a substance which acts upon the thyroid gland, diminishing its activity. Logically, we think, we may conclude that the milk of goats with intact thyroids must contain a substance antagonistic to the substance contained in the milk of thyroidless goats. Such a substance is the thyroid secretion. Besides thyroid secretion the milk also contains important nutritive substances, like albumin, milk-sugar, and fat; also lecithin, etc., certain ferments, and mineral matters, as lime, magnesia, iron, etc. (see, also, chapter on animal food). The valuable ferments which facilitate the digestion of the milk are, however, only contained in raw milk, and to a less extent in milk which is heated above 75° C. Behring has shown that even this temperature, if maintained as long as thirty minutes, is apt to deteriorate the milk. Pasteurized milk that is never heated above 70° C., and is cooled immediately afterward, contains a considerable amount of these important ferments. But if milk is heated to higher temperatures, as happens in boiling, the ferments are killed. It is of the greatest significance that raw milk has also the property to kill microbes to a certain extent. Thus Walter Hesse found in 1894 that the microbes of cholera died in raw milk. In experiments he has made recently with Hemp,[292] it was shown that raw milk of certain kinds of cattle had also the property to kill the bacilli of typhoid fever. But it is of the utmost importance to remember that these bactericidal properties of raw milk are destroyed if the milk is heated to 60° C. (140° F.). These authors have found that refrigerated milk, even if it is cooled down from 70° C., does not lose its bactericidal properties. Footnote 292: Hemp: Verhandlungen des Congresses Deutscher Naturforscher und Aertze, Dresden, vol. i, p. 112, 1907. There is a wonderful difference in the effects of boiled and raw milk. Animals, or children, never thrive so well on boiled as on raw milk. Professor Behring, of Marburg,[293] has shown that animals fed on milk heated to a high temperature never thrive well. Calves have been reared in Marburg, or on Bohemian or Hungarian farms, on boiled milk, and others on raw milk. Experiments with hundreds of such calves have shown that boiled milk is not a suitable food for them. Footnote 293: Behring: Beiträge zür experimentellen Therapie, 8 fl, 1906.