could be removed, but slowly by the processes of chemical nonvital oxidation. Even the parasites are not wholly evils, for some of these man has already tamed and compelled to perform some of the most important domestic operations—the raising of bread and the making of cheese and vinegar. Alcohol is one product of the activity of yeasts, and to these we owe our wines and beers. The precision in the manufacture and the uniform quality of the product of bread, cheese, vinegar, and beer have come only within recent decades when the microscopic organisms upon which these processes depend have become known and regularly raised like wheat and cattle. Recent investigations plainly suggest that greater precision and more uniform success can be obtained in the production of wines and in the curing of tobaccos. Doubtless we have but begun to domesticate the plant parasites which can be made useful to man, and more extended investigations will probably show that many processes in the domestic and other arts which are now tardy and uncertain can be carried on rapidly and accurately.
The science of bacteriology has now become so specially developed along medical lines that in this aspect it can scarcely be counted longer a part of botany; but we should not forget that the first knowledge of the bacteria came through botanists, and that the methods now employed in studying and combating them were first suggested by botanists, and every teacher of botany should regard it both a duty and a privilege to spread among his pupils and the public in general such a knowledge of the habits and effects of these minute organisms that public sentiment will demand not only personal but municipal cleanliness. An adequate supply of water, free from contamination at its sources and in its passage to our houses, contributes not only to the comfort, but greatly also to the health, of any community. The installation of a system of sewerage, for the safe disposal of the extremely dangerous waste matters of houses and stables, will come as soon as public sentiment is enlightened as to the probability of fatal disease resulting from the infection of drinking water, milk, and other uncooked foods from such decaying matters. It is now known that street dust contains millions of organisms which, when they find lodgment in human bodies, made suitable by weakness for their growth, cause the most malignant maladies. Even the dust of our rooms contains numberless organisms of these same sorts. So it behooves us as intelligent people to strive to bring about such cleanliness of streets and houses that these dangers will be reduced to a minimum.
The bacterial and fungous diseases of other animals than man, and the diseases of plants, are still being studied by botanists. We have only begun to know the dangers which menace the
