be injected back into a healthy
person where, in due time, they cause the disease. The germs feed inside
the red blood corpuscles and at regular intervals they destroy a large
number of these causing a chill which is followed by fever and a new
supply of corpuscles is produced. This alternation of chill and fever
may continue all summer, if medicine is not taken to destroy the germs.
Quinine will kill the germs if it is taken so that plenty of it is in
the blood when the germs come out of the torn down corpuscles during a
chill.

In order to prevent malarial fever, get rid of the mosquitoes by
draining and oiling the breeding places, escape their bites by screening
houses, smudging and destroying the adults, and keep the mosquitoes
from patients who have the fever. This is almost as important as the
destruction of the mosquitoes. The malarial fever mosquitoes are as
harmless as our common forms so long as they do not become infected with
germs by sucking blood from a fever patient.

[Illustration: Mosquitoes in position for biting; a, common Culex
mosquito; b, malarial fever mosquito. Note that the one stands parallel,
while the other stands at an angle to the surface on which it rests.]

In view of the fact that most of our common mosquitoes are classed as
non-dangerous, it is of interest to know just how to distinguish the
harmless ones from the dangerous. The adults of the two forms can be
easily distinguished when they are seen at rest. The common forms always
rest with the body parallel to the surface on which they rest, while the
malarial form always elevates the end of the body so that the head is
pointed toward the surface on which it rests. In like manner the
wigglers can be distinguished from each other. Our common wigglers
always hang head downward in the water while those of the malarial
mosquitoes rest near the surface of the water with their bodies parallel
to it. The majority of the wigglers found in rain barrels are of our
common forms.

[Illustration: Common Culex mosquito showing stages of development; a,
raft of eggs; b, larvae or wigglers of different sizes; c, pupa; d,
mosquito. The large wiggler and the pupa are taking air from the surface
of the water through their breathing tubes.]

The life of the mosquito is quite interesting and is an excellent
example of an insect which lives in the water part of its life and in
the air the rest. The mature female mosquito, which does all the
biting, s