intestine some weeks previously at the commencement of the outbreak of the disease in Egypt. Though living in him the cholera-bacilli had not found a favourable field of growth. This man in handling the cold broth, the cloth used to rub the spoon with which it was stirred, or the basin itself, had, it was found by making the actual experiment, been able to transfer the minute bacillus to the cold broth, a most favourable and nourishing medium for its growth, and so his isolated carefully guarded employer received an abundant crop of the bacilli and developed a fatal attack of cholera. Had the lady taken the broth hot, there would have been no living cholera-bacillus in it, and if she had thus guarded herself in regard to all food, by the use of heat and great cleanliness, she would have escaped infection. The most interesting development of knowledge and speculation with regard to the microbes which infest the human intestine and other regions of the human body is (as I mentioned above) connected with the fact that one kind or species of microbe has the power of favouring the growth of another, if present alongside of it, and that another kind has the power of checking or antagonising its growth. Thus common putrefactive microbes of river water are hostile to the cholera-bacillus and to the typhoid-bacillus. Those disease-producing bacilli live longest and best in very pure water! Thus, too, it is found that the microbe of sour milk—the lactic-bacillus—is antagonistic to the common putrefactive microbe of the intestinal contents—the well-known bacillus coli. In virtue of the acid which it produces, the microbe of sour milk arrests the excessive growth and activity of the putrefactive bacillus coli. Hence the utility of sour milk in many cases of intestinal trouble. We contain within us a microbian flora of such variety and abundance of kinds and so nicely balanced in their antagonisms and co-operations in a healthy man, that one cannot wonder at the timidity of the medical man who hesitates to interfere with their conflicts and established _modus vivendi_. Yet that seems to be the direction in which action will have to be taken. It seems likely that in different localities—towns, forests, highlands, lowlands, seaboards—there are prevalent different microbes which enter the bodies of human visitors and act as disturbers of the native microbian flora previously established in the stranger.