We live in a world that is teeming with life. From the earliest times of man that life has been studied and the observations recorded. Thus there has slowly come to be a considerable accumulation of knowledge concerning the various forms (morphology) and functions (physiology) of organised life. This we call the science of biology. It has for its object the study of organic beings, and for its end the knowledge of the laws of their organisation and activity. Slowly, too, in the midst of this gradual accumulation of facts, we begin to see incoherence becoming coherent, chaos becoming cosmos, chance and accident becoming law. Further, the contemplation and comprehension which built up the edifice of modern biology is assuming a new relationship to practical life. Biology can no longer be considered only as an academic occupation or as a theoretical pabulum upon which the leisured mind may ruminate. With rapid strides and determined face this giant of knowledge has marched into the arena of practical politics. The world is opening its eyes to a reality which it had mistaken for a vision.

This application of biology to life and its problems has in recent years been nowhere more marked than in the realm of bacteriology. This comparatively new science, associated with the great names of Pasteur, Koch, and Lister, furnishes indeed a stock illustration of the applicability of pure biology. Turn where we will, we shall find the work of the unseen hosts of bacteria daily claiming more and more attention from practical people. Thus biology, even when clothed in the form of microscopic cells, is coming to occupy a new place in the minds of men. "Its evolution," as Professor Patrick Geddes declares, "forms part of the general social evolution." Certainly its recent rapid development forms a remarkable feature in the practical science of our time. Not only in the diagnosis and treatment of disease, nor even in the various applications of preventive medicine, but in ever-increasing degree and sphere, micro-organisms are recognised as agents of utility or otherwise no longer to be ignored. They occur in our drinking water, in our milk supply, in the air we breathe. They ripen cream, and flavour butter. They purify sewage, and remove waste organic products from the land. They are the active agents in a dozen industrial fermentations. They assist in the fixation of free nitrogen, and they build up assimilable compounds. Their activity assumes innumerable phases and occupies many spheres, more frequently proving themselves beneficial than injurious. They are both economic and industrious in the best biological sense of the terms.

Yet bacteriology has its limitations. It is well to recognise this, for the new science has in some measure suffered in the past from over-zealous friends. It cannot achieve everything demanded of it, nor can it furnish a cause for every disease. It is a science fuller of hope than proved and tested knowledge. We are as yet only upon the threshold of the matter. As in the neighbouring realm of chemistry, it is to be feared that bacteriology has not been without its alchemy. The interpretations and conclusions which have been drawn from time to time respecting bacteriological work have led to alarmist views which have not, by later investigation, been fully supported. Again, the science has had devotees who have fondly believed, like the alchemists, that the twin secret of transmuting the baser metals into gold and of indefinitely prolonging human life was at last to be known. But neither the worst fears of the alarmist nor the most sanguine hopes of the alchemist have been verified. Science, fortunately, does not progress at such speed, or with such kindly accommodation. It holds many things in its hands, but not finally life or death. It has not yet brought to light either "the philosopher's stone" or "the vital essence."

What has already been said affords ample reason for a wider dissemination of the elementary facts of bacteriological science. But there are other reasons of a more practical nature. Municipalities are expending public moneys in water analysis, in the examination of milk, in the inspection of cows and dairies, in the bacterial treatment of sewage, and in disinfection and other branches of public health administration. Again, the newly formed National Association for the Prevention of Tuberculosis, our increasing colonial possessions with their tropical diseases, even medical science itself, which is year by year becoming more preventive, make an increasing claim upon public opinion. The successful accomplishment and solution of these questions depend in a measure upon an educated public opinion respecting the elements of bacteriology. Recently it was urged that "the first elements of bacteriology should be shadowed forth in the primary school."1 This course was advised owing to such knowledge being of value to those engaged in dairying. As we shall point out at a later stage, many of the undesirable changes occurring in milk are due to bacteria, even as the success of the butter and cheese industries depends on the use and control of the fermentative processes due to their action. Much of the uncertainty attending the manufacture of dairy products can only be abolished by the careful application of some knowledge of the flora of milk. In Denmark and in Scandinavia the importance of such knowledge is realised and acted upon. America, too, has not been slow to respond to these needs; but in England comparatively little has been done in this direction.2

Whilst there can be no doubt as to the advantage of a wider dissemination of the ascertained facts concerning bacteria, it should be borne in mind that only patient, skilled observation and experimental research in well-equipped laboratories can advance this branch of science, or indeed train bacteriologists. The lives of Darwin and of Pasteur adequately illustrate this truth. Yet it is observable that States and public bodies are slow to act upon it, and frequently in the past the most useful and substantial support for the advancement of science has been forthcoming only from private sources. As the world learns its intimate relation to science and the interdependence between its life and scientific truth, it may be expected more heartily to support science.

BACTERIA