CONTENTS

INTRODUCTION

CHAPTER I

What bacteria, microbes, and germs are Their ances-

try and evolution - The living earth and the function of

bacteria in nature - The origin and evolution of para-

sitic and disease-producing bacteria - The microscope,

the telescope, the theory of spontaneous generation, and

the rise of the science of Bacteriology.

CHAPTER II

The forms and the appearance of bacteria — Cocci, ba-

cilli, and spirilla - The size and weight of bacteria -

How bacteria grow and multiply - Their rate of growth

- Influences restraining multiplication - How bacteria

-

move: their rate of motion Bacterial spores and bac-

terial hibernation - Longevity.

CHAPTER III

The temperature range of microbic life — Arctic snow

and thermal springs - Pasteurization and the preserva-

tion of milk - Freezing and thawing and the effect of

liquid air upon bacteria - Purification of water by freez-

ing · Cold storage Desiccation and food preserva-

tion Effect of strong salt solutions upon bacteria-

Effect of strong sugar solutions upon bacteria -

vation of food by corning - Light without heat.

CHAPTER IV

-

Preser-

The physics of bacteria - Relations between surface,

volume, and the energy requirements of bacteria - The

nutrition of bacteria Nutritive substances - The mi-

crobic Dr. Jekyll and Mr. Hyde- Purification of sew-

age by bacteria - Food poisoning and food flavors.

CHAPTER V

The nutrition of bacteria, continued - Toxin and anti-

Vital specificity of bacteria

toxin

-

Microbes and

Polarized light - The

sugars Structure of sugars ·

polarimeter Optical properties of sugars

as sugar chemists.

XV

I

12

27

45

69

CHAPTER VI

The life cycle of the earth- The living earth and the

rotation of the elements in the life cycle- The nitrogen

cycle: nitrogen-fixation by the leguminous plants and

the nodule bacteria The clover-bacteria complex

The sulphur and iron and phosphorus cycles.

CHAPTER VII

-

--

Sewage and civilization — Bacterial purification of sew-

age History of the development of sewage purifica-

tion

Importance of bacteria in the process

-

-

Count-

ing living bacteria Purification of drinking-water by

Effects of biological filters upon the health

How biological filters work.

bacteria

--

of the community

CHAPTER VIII

--

The

Bacteria and the industries - The retting of flax

tanning of leather The manufacture of synthetic rub-

ber The manufacture of vinegar Bacterial diseases

of plants.

-

CHAPTER IX

The disintegration of animal and vegetable remains by

bacteria Lactic acid Nature's preservative Its

chemistry - The history of the preservation of milk by

lactic acid Lactic-acid bacteria of the alimentary

canal of man — Lactic-acid bacteria and the churning

of cream

The part played by lactic-acid bacteria in

the preparation of sauerkraut The preservation of

ensilage by lactic-acid fermentation.

The bacteria of the alimentary canal of man The re-

markable efficiency of the intestinal incubator The

significance of the bacteria in the alimentary canal —

Germ-free chicks, turtles, and guinea pigs - The impor-

tance of the bacteria in the alimentary canal of the in-

fant - Lactic-acid bacteria and the prolongation of life.

CHAPTER XI

Man's microbic associates and antagonists-Soil bac-

teria and the evolution of parasitic and pathogenic

bacteria - The cycle of perpetuation of parasitic bac-

teria

The cycle of perpetuation of pathogenic bac-

teria The cycle of infection with intestinal bacteria

The cycle of infection with pathogenic bacteria of the

-

--

--

86

103

124

141

155

168

-

respiratory tract Droplet infection — Tubercle bacilli

and tuberculosis - Summary of the essential factors of

intestinal and respiratory infections

tact infection.

CHAPTER XII

Plague

-

· Con-

Immunity, susceptibility, and resistance to infection -

The origin of microbiphobia - Susceptibility and resist-

ance to microbic invasion-The general phenomena

of resistance to bacterial infection— Natural, individual,

and acquired immunity - Defenses of the body against

infection with parasitic bacteria - The offense of the

body against invasion by progressively pathogenic bac-

teria - The production and use of antitoxin

of immunity and their relation to parasitic and patho-

genic bacteria.

CHAPTER XIII

nature

-

--

Theories

193

209

Balanced parasitism-The importance of balances in

-The effects of unbalance - Disturbed balances

by the introduction of alien species - The eradication

of alien species and the reëstablishment of balance

The nature of the microbic balance with mankind - The

complexity of the microbic balance; meningococcus

strains and meningococcus balances - The importance

of serologic strains among microbes and their effects
upon the man-microbic complex - Summary and con-
clusion - The dawn and development of microbiphilia.

INDEX

225

ILLUSTRATIONS

MASTERS OF THE MICROBE: EHRLICH, PASTEUR, THEOBALD SMITH, KOCH, METCHNIKOFF Frontispiece

THE FORMS OF BACTERIA

From Fraenkel and Pfeiffer's Atlas of Bacteria

14

CLOVER PLANT SHOWING Nodules upon ROOTS
From a drawing by Ivan E. Wallin

94

SECTION OF ROOT NODULE OF CLOVER PLANT
SHOWING NUMEROUS NODULE (NITROGEN-FIX-
ING) BACTERIA

98

From a drawing by Ivan E. Wallin

CULTURE PLATE SHOWING BACTERIA DEVELOPING
FROM ONE TEN-THOUSANDTH OF A CUBIC CEN-