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- The Story Of Germ Life - 1/26 -


THE STORY OF GERM LIFE

BY H. W. CONN

PROFESSOR OF BIOLOGY AT WESLEYAN UNIVERSITY,

AUTHOR OF EVOLUTION OF TO-DAY, THE LIVING WORLD, ETC.

PREFACE.

Since the first edition of this book was published the popular idea of bacteria to which attention was drawn in the original preface has undergone considerable modification. Experimental medicine has added constantly to the list of diseases caused by bacterial organisms, and the general public has been educated to an adequate conception of the importance of the germ as the chief agency in the transmission of disease, with corresponding advantage to the efficiency of personal and public hygiene. At the same time knowledge of the benign bacteria and the enormous role they play in the industries and the arts has become much more widely diffused. Bacteriology is being studied in colleges as one of the cultural sciences; it is being widely adopted as a subject of instruction in high schools; and schools of agriculture and household science turn out each year thousands of graduates familiar with the functions of bacteria in daily life. Through these agencies the popular misconception of the nature of micro- organisms and their relations to man is being gradually displaced by a general appreciation of their manifold services. It is not unreasonable to hope that the many thousands of copies of this little manual which have been circulated and read have contributed materially to that end. If its popularity is a safe criterion, the book has amply fulfilled its purpose of placing before the general reader in a simple and direct style the main facts of bacteriology. Beginning with a discussion of the nature of bacteria, it shows their position in the scale of plant and animal life. The middle chapters describe the functions of bacteria in the arts, in the dairy, and in agriculture. The final chapters discuss the relation of bacteria to disease and the methods by which the new and growing science of preventive medicine combats and counteracts their dangerous powers.

JULY, 1915.

CONTENTS.

I.--BACTERIA AS PLANTS

Historical.--Form of bacteria.--Multiplication of bacteria.--Spore formation.--Motion.--Internal structure.--Animals or plants?-- Classification.--Variation.--Where bacteria are found.

II.--MISCELLANEOUS USES OF BACTERIA IN THE ARTS.

Maceration industries.--Linen.--Jute.--Hemp.--Sponges.--Leather. --Fermentative industries.--Vinegar--Lactic acid.--Butyric acid.-- Bacteria in tobacco curing.--Troublesome fermentations.

III.--BACTERIA IN THE DAIRY.

Sources of bacteria in milk.--Effect of bacteria on milk.-- Bacteria used in butter making.--Bacteria in cheese making.

IV.--BACTERIA IN NATURAL PROCESSES.

Bacteria as scavengers.--Bacteria as agents in Nature's food cycle.--Relation of bacteria to agriculture.--Sprouting of seeds. --The silo.--The fertility of the soil.--Bacteria as sources of trouble to the farmer.--Coal formation.

V.--PARASITIC BACTERIA AND THEIR RELATION TO DISEASE

Method of producing disease.--Pathogenic germs not strictly parasitic.--Pathogenic germs that are true parasites.--What diseases are due to bacteria.--Variability of pathogenic powers.-- Susceptibility of the individual.--Recovery from bacteriological diseases.--Diseases caused by organisms other than bacteria.

VI.--METHODS OF COMBATING PARASITIC BACTERIA

Preventive medicine.--Bacteria in surgery.--Prevention by inoculation.--Limits of preventive medicine.--Curative medicine. --Drugs--Vis medicatrix naturae.--Antitoxines and their use.-- Conclusion.

THE STORY OF GERM LIFE.

CHAPTER I.

BACTERIA AS PLANTS.

During the last fifteen years the subject of bacteriology [Footnote: The term microbe is simply a word which has been coined to include all of the microscopic plants commonly included under the terms bacteria and yeasts.] has developed with a marvellous rapidity. At the beginning of the ninth decade of the century bacteria were scarcely heard of outside of scientific circles, and very little was known about them even among scientists. Today they are almost household words, and everyone who reads is beginning to recognise that they have important relations to his everyday life. The organisms called bacteria comprise simply a small class of low plants, but this small group has proved to be of such vast importance in its relation to the world in general that its study has little by little crystallized into a science by itself. It is a somewhat anomalous fact that a special branch of science, interesting such a large number of people, should be developed around a small group of low plants. The importance of bacteriology is not due to any importance bacteria have as plants or as members of the vegetable kingdom, but solely to their powers of producing profound changes in Nature. There is no one family of plants that begins to compare with them in importance. It is the object of this work to point out briefly how much both of good and ill we owe to the life and growth of these microscopic organisms. As we have learned more and more of them during the last fifty years, it has become more and more evident that this one little class of microscopic plants fills a place in Nature's processes which in some respects balances that filled by the whole of the green plants. Minute as they are, their importance can hardly be overrated, for upon their activities is founded the continued life of the animal and vegetable kingdom. For good and for ill they are agents of neverceasing and almost unlimited powers.

HISTORICAL.

The study of bacteria practically began with the use of the microscope. It was toward the close of the seventeenth century that the Dutch microscopist, Leeuwenhoek, working with his simple lenses, first saw the organisms which we now know under this name, with sufficient clearness to describe them. Beyond mentioning their existence, however, his observations told little or nothing. Nor can much more be said of the studies which followed during the next one hundred and fifty years. During this long period many a microscope was turned to the observation of these minute organisms, but the majority of observers were contented with simply seeing them, marvelling at their minuteness, and uttering many exclamations of astonishment at the wonders of Nature. A few men of more strictly scientific natures paid some attention to these little organisms. Among them we should perhaps mention Von Gleichen, Muller, Spallanzani, and Needham. Each of these, as well as others, made some contributions to our knowledge of microscopical life, and among other organisms studied those which we now call bacteria. Speculations were even made at these early dates of the possible causal connection of these organisms with diseases, and for a little the medical profession was interested in the suggestion. It was impossible then, however, to obtain any evidence for the truth of this speculation, and it was abandoned as unfounded, and even forgotten completely, until revived again about the middle of the 19th century. During this century of wonder a sufficiency of exactness was, however, introduced into the study of microscopic organisms to call for the use of names, and we find Muller using the names of Monas, Proteus, Vibrio, Bacillus, and Spirillum, names which still continue in use, although commonly with a different significance from that given them by Muller. Muller did indeed make a study sufficient to recognise the several distinct types, and attempted to classsify these bodies. They were not regarded as of much importance, but simply as the most minute organisms known.

Nothing of importance came from this work, however, partly because of the inadequacy of the microscopes of the day, and partly because of a failure to understand the real problems at issue. When we remember the minuteness of the bacteria, the impossibility of studying any one of them for more than a few moments at a time --only so long, in fact, as it can be followed under a microscope; when we remember, too, the imperfection of the compound microscopes which made high powers practical impossibilities; and, above all, when we appreciate the looseness of the ideas which pervaded all scientists as to the necessity of accurate observation in distinction from inference, it is not strange that the last century gave us no knowledge of bacteria beyond the mere fact of the existence of some extremely minute organisms in different decaying materials. Nor did the 19th century add much to this until toward its middle. It is true that the microscope was vastly improved early in the century, and since this improvement served as a decided stimulus to the study of microscopic life, among other organisms studied, bacteria received some attention. Ehrenberg, Dujardin, Fuchs, Perty, and others left the impress of their work upon bacteriology even before the middle of the century. It is true that Schwann shrewdly drew conclusions as to the relation of microscopic organisms to various processes of fermentation and decay--conclusions which, although not accepted at the time, have subsequently proved to be correct. It is true


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