The record-union., 1899-10-16

Since it has been eStaDHSheu ny SNAS
tific demonstration that certain klhds
of mosquitoes carry TO human pelAe9
the malarial parasite, and that II such
mosquitoes are destroyed in the larvae
stage. malarial fever will disappear,
scientific treatment of the subject De-
comes of profound interest. =,
We therefore reprint from Nature
an article upon the subject, and also
from the same scientific journal two
paners bv Major Ronald Ross, the lat
est investigator in this direction. Major
Ross is an English army surgeon and
prosecuted his research mainly IN Indla
during the past three and half years
Mature" says:
PRESENT POSITION OF THE IN
VESTIGATION.
The role played by the mosquito as a
carrying agent Of the malarial parasite
from man to man seems to be restricted
to one genus, the anopheles Major
Ross Of the Liverpool School Of Tropical
Diseases, in a telegram from Sierra
Leone, announces the fact that he has
found the anopheles there, and that it
may be the intermediary host Of the
quartan malarial fever.
Many observers in different countries,
noticing the fact that malaria is most
prevalent at the most active period OF
mosquito life, have attributed malaria
to the agency of this insect. DR.. Pat
rick Manson, in 1894, first brought the
subject forward in England, and, acting
on his suggestion and advice, Major
Ross undertook an investigation in In
dia-
In 1897, by using two species Of
anopheles, Ross traced the malarial
parasite into the wall of the stomach
of the mosquito after it had fed on
patients whose blood contained the
crescentic gametocytes; the next year
he succeeded in tracing the complete
life history Of the proteosoma CRASH
Liable of sparrows, and showed that It's
intermediary host was one particular
kind Of mosquito, the Culex pipiens. The
gametocytes contained in the red blood
cOrpuscles Of the vertebrate host pass
with the blood into the stomach Of the
mosquito, and passing through the
stomach-wall bulge into the body-cav-
ity; here a sexual process takes place,
zygotoblasts are eventually formed,
which pass into the insects blood, and
finally find their way into the salivary
gland and to the duct leading from this
to the extremity of the stylet; from
here they escape into the blood of the
vertebrate host when the insect bites.
Following on these results, Grassi in
Italy attacked the problem from an
other point Of view; he studied the mos
quitoes prevalent in the different parts
of the country where malaria, occurs.
The results were interesting. He found
there was no indigenous malaria where
the Culex pipiens was common, but il
did occur where the large mosquito
anopheles was found.
Bignami and BastianelI, who had
been trying unsuccessfully to infect a
man by allowing mosquitoes to bite
him, attributing their want of success
to the use of the wrong kind of mos
quito, and, acting on the observations
of Grassi, tried again with some mos
quitoes imported from a malarious dis
trict. This time they succeeded in in
fecting the man with malaria of the
same type that prevailed in the district
from which the mosquitoes came More
over they have shown that the develop
ment of the human form of parasite in
the body of anopheles is identical with
Z
birds in Culex pipiens, as observed by
Ross.
According to these observers, the
species Anopheles claviger is the mos
common intermediary host of the para
site Of malaria in Italy, the tertian and
summer-autumn types.
1t is evident that the next step in the
study of malaria should be to hunt fol
the different species of anopheIes and
see if these are the Intermediary hosts o
the different types Of malaria through
out the world, and what particular
species is most concerned in transfer
ring the parasite from man to man
Grassi has done this for Italy, and nou
we hear that Ross has found a species
of anopheles to be concerned in tn,
transference Of quartan fever; thus al
the types Of malarial fever are now re-
ferred to the anopheles as their inter
mediary host. His full report on return
from Africa will be read with interest
Whether the anopheles can be extir-
pated from a locality, and by what
means, win be the problem for scien
tific workers resident abroad to settle
fortunately they seem to be confined Il
small areas, SO the suggestion of Ros!
10 draw off the water from stagnan
pools may not be so hopeless a task a,
it would at first appear.
MAJOR ROSS GIVES THE LIFE
HISTORY OF THE PARASITE.
The parasites which cause malaria
fevers in human beings belong to
very homogeneous group, other spec
les of which are found in certain bat
and birds. The life history of tn
three species of this group which hav
been completely studied is as follows
The youngest parasites exist as amoe
bulae or myXopods within the re,
blood corpuscles of the vertebrate host
Each amoebula possesses a nucleus an
nucleolus; and its movements vary il
extent and rapidity with the species
but, in the case of birds, never en-
croach upon the nucleus Of the cor
puscle The amoebulae increase Il
size; and, as they do so, tend to los
their movements and to accumulate i
their ectoplasm certain black granules
the pigment or melanin which are tn
product of assimilation of the haemo
globin of the corpuscle. In from on
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