The record-union., 1899-10-16
MALARIA AND MOSQUITOES.

some years ago aHnOunCeu' -
that the mosquito was the chief vehicle
for conveyance Of the parasite 1t was
received by laymen with incredulity. 1t
is. however, now known to be estab-
lished fact It seems strange, says the
"Sanitarian," in considering the sub
ject, that man should so long nave
remained in ignorance of the truth re-
garding the form and mode by which
these parasites existed outside of the
human body and independently of it.,
and how they gained entrance into it.
Yet when we reflect upon the Won
drous strides of scientific research in
latter years, We cannot agree with the
"Sanitarian" that there is any thing
specially strange in the fact that the
full discovery of the truth should date
in our own time, since it must have
a beginning in the record of knowledge.
But the theory that the mosquito is
the conveyor of the seeds Of the aftlic-
tion, while coming to most laymen as
new, is in fact not novel or Of recent
origin. It was advanced by some of
the ancient Roman writers who had
pretty accurate knowledge Of malaria.
theory with respect. The peasants of the
Tyrol and of parts of italy and some
barbarous tribes in malarious districts
hold that mosquitoes convey the disease
to human beings, and many learned
men in England, Italy Germany and
some in our own country long ago held
to the same belief.
But in the broad sense the doctrine
has not been known to the mass Of our
people and when suggested has been,
until recently, received with scofhng.
If the cattle of the field may he in
fected with fever by the bite of a tick,
why not man by the bite Of the mos
quito?
In 1894 Manson expounded the theory
that the organisms of malaria divide
their existence between man and the
mosquito. He and others held that the
human infection took place by way Of
drinking water infected by mosquitoes
which had sucked up malarial blood and
died after laying their eggs in the
water; or by inhalation of dust, pro-
duced by the drying up of small pools
which once contained infected water.
But while Manson's ideas pointed the
way to the truth, the greater distinc-
ton Of true discovery was reserved for
Ronald Ross. an English army surgeon
in India who in the last three years
has cleared away all doubts and dis
placed theory by demonstrated truth.
The "Sanitarian" sums up the results
Of his work, which extended over a
large area ana involved the most Ia
borious and painstaking series of OBJ
servations, as follows:
The cultivation of the parasites Of
human malaria in the bodies of two
species of mosquitoes inoculated by
being allo- to suck the blood of ma
larial patients; in the infected mos
quito the parasites occurred as peculiar,
pigmented cells in the walls Of the
NNS-AA~ASA4. II CGN4uS MOSQUITOES on me
blood Of birds containing nenlatozoa
tHalteridium and especially Proteo-
soma), he traced the formation in the
walls Of the stomach Of large
cells, which fall asunder into spindle
shaped germinal rods
which are carried by the blood 70 the
saliyary glands, where they collect in
huge numbers and whence they are
discharged into the blood Of healthy
birds bitten by the infected mosquitoes.
1t required seven days or so after the
infection Of mosquito before the ger
minal rods or sporozoites reach the sa-
Iivary glands. and birds bitten by such
mosquitoes fail sick five or six days
afterward.
When Ross made public his discov-
cries they We're confirmed by all
scientists who examined his specimens,
and by all students who went over his
researches. Others made independent
studies and reached the same -conclu-
sions, and in this direction the Italian
physicians and scientists have been es-
pecially prominent. They have sue
ceeded in injecting persons with malaria
through the bite Of the infected mos
quito, and have traced the whole de-
velopment in the body of the insect. Of
the crescent, of the estivo-autunnaI
type, and partly Of the tertian para
sites. They have found young para
sites in the eggs of infected mosquitoes.
and have discovered the malarial para
site In the bodies of a large percentage
Of mosquitoes taken in rooms and local
tiles Inhabited by malarial patients
boss proves that not all kinds of mos
quitoes act as hosts Of these parasites.
There are many species, including the
common or domestic MOSQUITO. which
bear no relation to any known hemato-
zoon infection. The particular mos
quito which we must fight shy Of as
dangerous, is largely of the genus
anopheles, Of which there are many va
rieties. Whether other kinds of suc-
torlal insects are carriers of human
malaria has not yet been determined.
II Is unimportant to the layman how
the mosquito becomes infected and how
they perpetuate their infectiousness
through generations by transmission OF
the parasites in sort Of snoring form
TO the eggs of the female. What we
are concerned in is the publicity Of
knowledge enabling US to recognize the
mosquito Of the class that carries the
tF.xr~