t of view, 14.

CHAPTER II

BACTERIA AND PROTOZOA 15

_Bacteria_, 15; border line between plants and animals, 15;
most bacteria not harmful, 15; a few cause disease, 15; how
they multiply, 15; parasitic and non-parasitic kinds, 17; how a
kind normally harmless may become harmful, 18; effect of the
bacteria on the host, 18; methods of dissemination, 18; _Protozoa_,
19; _Amoeba_, 19; its lack of special organs, 19; where
it lives, 19; growth and reproduction, 19; _Classes of Protozoa_,
20; the amoeba-like forms, 20; the flagellate forms, 20; importance
of these, 21; the ciliated forms, 22; the Sporozoa or spore-forming kinds,
22; these most important, 23; abundance, 23; adaptability, 23; common
characters, 24; ability to resist unfavorable conditions, 24.

CHAPTER III

TICKS AND MITES 26

_Ticks_, 26; general characters, 27; mouth-parts, 27; habits,
27; life-history, 27; _Ticks and disease_, 28; _Texas fever_, 28; its
occurrence in the north, 28; carried by a tick, 29; loss and
methods of control, 31; other diseases of cattle carried by ticks,
31; _Rocky Mountain spotted fever_, 32; its occurrence, 32;
probably caused by parasites, 32; relation of ticks to this disease,
33; _Relapsing Fever_, 33; its occurrence, 34; transmitted
by ticks, 34; _Mites_, 35; _Face-mites_, 35; _Itch-mites_, 36;
_Harvest-mites_, 37.

CHAPTER IV

HOW INSECTS CAUSE OR CARRY DISEASE 40

Numbers, 40; importance, 41; losses caused by insects, 41;
loss of life, 42; _The flies_, 43; horse-flies, 43; stable-flies, 44;
surra, 45; nagana, 45; black-flies, 46; punkies, 46; screw-worm
flies, 47; blow-flies, 48; flesh-flies, 48; fly larvae in intestinal
canal, 49; bot-flies, 50; _Fleas_, 52; jigger-flea, 53; _Bedbugs_, 54;
_Lice_, 54; _How insects may carry disease_, 55; in a mechanical
way, 55; as one of the necessary hosts of the parasite, 56.

CHAPTER V

HOUSE-FLIES OR TYPHOID-FLIES 57

The old attitude toward the house-fly, 57; its present standing,
58; reasons for the change, 58; _Structure_, 59; head and
mouth-parts, 60; thorax and wings, 61; feet, 62; _How they
carry bacteria_, 62; _Life-history_, 63; eggs, 63; ordinarily laid in
manure, 63; other places, 63; habits of the larvae, 64; habits of
the adults, 64; places they visit, 65; _Flies and typhoid_, 65;
patients carrying the germs before and af