The food, therefore, has an influence on the microbes of the intestine. If the child be fed with cow’s milk, the flora is richer in species than in the case of a child suckled by its mother. Later on, also, the flora varies with the food, as has been proved by MM. Macfadyen, Nencki, and Mde. Sieber in the case of a woman with an intestinal fistula. The dependence of the intestinal microbes on the food makes it possible to adopt measures to modify the flora in our bodies and to replace the harmful microbes by useful microbes. Unfortunately, our actual knowledge of the intestinal flora is still very imperfect because of the impossibility of finding artificial media in which it could be grown. Notwithstanding this difficulty, however, a rational solution of the problem must be sought. Man, even in the savage condition, prepares his food before eating it. He submits much of it to the action of fire, thus notably lessening the number of microbes. Microbes enter the digestive tube in vast numbers with raw food, and in order to lessen the number of species in the intestines, it is important to eat only cooked food and to drink only liquids that have been previously boiled. In that way, although we cannot destroy all the microbes in the food, because some of them can withstand the temperature of the boiling point of water, we can kill the great majority of them. It has sometimes been supposed that cooked or completely sterilised food (that is to say food that has been subjected to a temperature of from 248°-284° Fahr.) is harmful to the organism and that much of it is not well digested. From this point of view protests have been made against the feeding of infants with sterilised milk or even with boiled milk. Although in certain cases sterilised milk is not well supported by infants, it cannot be doubted but that boiled milk and cooked food are generally successful. The large number of children brought up successfully on boiled cow’s milk and the health of travellers in arctic regions are ample proof of this. I have been told by M. Charcot that in his voyage to the antarctic regions, he and his companions lived entirely on sterilised food, or on cooked food such as the flesh of seals and penguins. As they had no green food nor fresh fruit, the only raw food that they ate was a little cheese. Living under these conditions, all the members of the expedition enjoyed good health, and there was no case of digestive disturbance in the whole period of sixteen months.