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 popularidea of bacteria to which attention was drawn in the originalpreface has undergone considerable modification. Experimentalmedicine has added constantly to the list of diseases caused bybacterial organisms, and the general public has been educated toan adequate conception of the importance of the germ as the chiefagency in the transmission of disease, with correspondingadvantage to the efficiency of personal and public hygiene. At thesame time knowledge of the benign bacteria and the enormous rolethey play in the industries and the arts has become much morewidely diffused. Bacteriology is being studied in colleges as oneof the cultural sciences; it is being widely adopted as a subjectof instruction in high schools; and schools of agriculture andhousehold science turn out each year thousands of graduatesfamiliar with the functions of bacteria in daily life. Throughthese agencies the popular misconception of the nature of micro-organisms and their relations to man is being gradually displacedby a general appreciation of their manifold services. It is notunreasonable to hope that the many thousands of copies of thislittle manual which have been circulated and read have contributedmaterially to that end. If its popularity is a safe criterion, thebook has amply fulfilled its purpose of placing before the generalreader in a simple and direct style the main facts ofbacteriology. Beginning with a discussion of the nature ofbacteria, it shows their position in the scale of plant and animallife. The middle chapters describe the functions of bacteria inthe arts, in the dairy, and in agriculture. The final chaptersdiscuss the relation of bacteria to disease and the methods bywhich the new and growing science of preventive medicine combatsand counteracts their dangerous powers.

JULY, 1915.

CONTENTS.

I.—BACTERIA AS PLANTS

Historical.—Form of bacteria.—Multiplication of bacteria.—Sporeformation.—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 foodcycle.—Relation of bacteria to agriculture.—Sprouting of seeds.—The silo.—The fertility of the soil.—Bacteria as sources oftrouble to the farmer.—Coal formation.

V.—PARASITIC BACTERIA AND THEIR RELATION TO DISEASE

Method of producing disease.—Pathogenic germs not strictlyparasitic.—Pathogenic germs that are true parasites.—Whatdiseases are due to bacteria.—Variability of pathogenic powers.—Susceptibility of the individual.—Recovery from bacteriologicaldiseases.—Diseases caused by organisms othe

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