While the medicinal value of water has perhaps been exaggerated, the possibility of its carrying disease, on the other hand, has been minimized. There are many diseases which are transmitted by germs of some kind or other or by direct infection. It is now established beyond doubt that the diseases which were known so long as malarial were misbranded. Of all the various forms of malarial diseases, none of them is caused by bad air. In earlier times when so many people were suffering from ague (chills and fever), it was noticed that in building houses in such regions the higher lands were selected - not only on account of beauty of view but for salubrity. Those who dwelt in the lowlands and near the waters were more subject to the "malarial" disease than those living at higher altitudes. This was popularly supposed to be due to the fact that the air in the lowlands was polluted. Since the epoch-making discovery of the activity of the mosquito in carrying diseases of this kind, it is now easily seen that those who lived in the lowlands and near the water supplies were very much more likely to be bitten by mosquitoes than those living on the highlands. Water therefore is only a side issue in the transmission of diseases by means of the mosquito in that it supplies the breeding places for the larvae of these insects. What is true of ague and chills and fever is also true of yellow fever, which is the result of a direct infection transmitted by a mosquito of another kind. The mosquito which produces the malarial fever is the variety known as anopheles, while that which produces the yellow fever is the stygomia. Another disease of a very dreadful character which is transmitted largely by water, in the opinion of most experts, is typhoid fever. Here, there is a direct infection through the water itself. The germs of typhoid fever live indefinitely in water, and even in ice. When these germs are taken into the alimentary canal they as a rule produce no effect. The perfectly healthy organism is either able to kill these germs or to prevent them from securing a hold. When, however, these germs come in contact with the organism in a certain state of fatigue or inability to resist, then they enter the intestine, propagate, and produce the well-known eruption on the small intestine which is characteristic of typhoid fever. Another disease which is supposed to be largely carried by water is cholera. Just in what way the germ is transmitted does not seem to be clear, but that water is the principal vehicle is believed by many. The many forms of diarrhoea, both infantile and adult, are doubtless produced often by water. In fact very often the diarrhoea which attacks travelers is ascribed to a change of water, though perhaps this is not always the case. But at least the possibility of transmission of diseases in this way through water must be considered. There are perhaps many other forms of diseases which depend more or less for their distribution upon the water supply, but those mentioned above are the most deadly and the most common. If therefore we accord to certain waters therapeutic or remedial effects, we must accord to certain others pathologic or disease effects. The object which must be kept in view in such cases would be to increase the consumption of waters that have therapeutic effects, and to decrease or eliminate completely the consumption of waters which are dangerous to health. Both of these events are capable of accomplishment by the application of industry, knowledge and skill. It seems only reasonable to believe that the advance of hygienic, therapeutic and engineering knowledge and skill will in the course of a few years eliminate most of the dangers incident to the drinking of water.