The sun., 1909-02-21


which some authorities, indeed mosi
authorities, look cd upon as a moribund
conditlon OF the parasite, or what they
called the agony form Of the parasite. Il
only occurs when the blood has been with.
1rawn from the human body. Certain
cumstanoes escape from the blood cor.
pusclee; They. become as II were
agitated. wriggle and move about. Then
suddenly they may throw out long,
swinging. lashing arms. many OF which
may break away and swim about as
independent bodies
NOW as this peculiar phenomenon 90
CURED only when the parasite was with
drawn from the human body, many au-
thorities. as have said, looked upon this
appearance as an indication OF the agony
preceding the death OF the parasite la
the abnormal and uncongenial oondi-
lions IN which 1t found itself. ! spent
| yentured to interpret the facts In quite
Hlmerent way. / reasoned:
Inc malaria parasite, like the filaria.
70 pass from man to man, must somehow
leave the human body. 1t is incapable
OF doing 80 by virtue of its own effort.
Of the blood. as the filaria Is enclosed
IN sack. Therefore some blood suck
ing animal, probably the mosquito,
which frequents the haunts Of malaria,
may be this particular agent, and be-
cause these agony forms-hagellated
bodies they were called-oome into ex-
lstence only whom the parasite has been
removed from the human body they
must be the earliest form Of the extra
corporeal phase of the malaria parasite.
MOSQUITO MALARIA THEORY.
About this time I met Prof. Ronald
Ross and had many talks with him on
tne malaria problem and others. ! sug-
gested 10 him that, falling human sub
lects. he might work out the life history
S1 sIossIS she SIorTesponding parasites in birds
after a time Prof. Ross took up this idea.
which he worked out to the brilliant CON
clusion which all the world knows.
be traced the malaria Of birds into
the mosquito. He traced II from the mos
quito stomach into the salivary glands.
down the proboscis and back again into
the bird. To show that the same thing
applied TO the parasite Of human malaria
was almost q work Of supererogation.
HAVANA FREED FROM YELLOW PEvKR.
The success Of the mosquito theory
both as regards filari@ and malaria
meant that the idea Of insect transmission
was not TO stop at these two diseases. A
good many years ago it occurred 70
rmdlay OF Havana that the mosquito
OF that country might be the agent for
the spread OF yellow fever, just as had
shown 1t TO be the means by which filarie
are spread. He made several experiments,
some OF which seemed TO countenance
the idea, but the subject was not then
proceeded with.
Some years ago an American commits
sion which had been sent out TO study
yellow fever took the matter up again
and has shown that q certain kind OF
mosquito IL 1t feeds on a yellow fever
patient during the first three days OF
the disease contracts the virus Of yellow
fever; that II this insect 90 infected is
kept for some ten or twelve days. being
carefully fed the while, and is then allowed
to bite some one who has never had
yellow fever 1t will confer yellow fever
on the individual 90 bitten. That discovery
has rid Havana Of yellow fever. and that
discovery is enabling the Americans TO
construct the Panama Canal.
TERRoRs AND REMEDIES OF THE FUTURE.
THE success Of these invest cations in
the case Of the mosquito has stimulated
further work on other bloodsucking
insects and now We know Of a good
many other diseases which are 80 trans
ferred. We know that a certain tick
conveys an important disease OF cattle
Texas fever-which prevails in many
parts OF the world. making serious inroads
on pastoral industry. We know that a
similar disease In dogs is conveyed by
There is proof that the tsetse fly acts |
in like manner as regards the fly diseases |
Of cattle and the fly disease-the sleeping |
siCkness-of man We know that a GER |
tain Kind of tick is the medium by which |
most serious kind OF African fever
fairly sure that other diseases are con-
vetyed by bugs and lice and 30 on.
Almost every month fresh discovery |
OF this description is being made. and |
doubtless the result will be practical |
measures which will tend TO minimize |
the dangers of these diseases. II not
actually succeed in preventing them !
Hundreds Of workers are now busyipg |
themselves with these problems. -.
Those Of us who have seen the progress
Of events of late years In Africa have been |
struck with the remarkable way In which |
diseases which had hitherto been confined
to very limited areas are gradually ex-
tending over a greater part OF the conti- |
nent This undoubtedly is the result Of
the moving Of the population, Of increased
facilities of travel and 90 forth-the
opening up Of the Dark Continent.
What is happening in Africa Will hap
pen elsewhere. Increased facility for
rapid travel implies the spread Of disease.
Thereare several tropical disoasee. notably
malaria and yellow fever-both mosquito
borne diseases-which are still geograph-
ically limited; that is to say. there are
places where they do not occur. For
instance there Is no yellow fever In Asia
or east Africa. As regards malaria il
does not exist in many OF the Pacific |
Islands; Fiji for one Is free.
MY belief is that II precautions are not |
taken In time both Of these diseases.
yellow fever and malaria, will extend their |
range, that with the opening up OF the
Panama Canal and by the repeated passage
Of rapid steamers across the Pacific yell
low fever will be introduced into the Sand
wich Islands, Manila and to the continent
Of Asia. My belief also is that IL measures
are not taken TO prevent the introduction
OF fever carrying mosquitoes into some
countries hitherto free from malaria
by and by these countries will become
instead Of healthy exceedingly unhealthy
and malarious-that the experience OF the
Aiauritius will be paralleled.
sYou know in the time OF Paul and
Virginia the Mauritus was a veritable
heaven upon earth. At the present time
rs regards health. this island is certainly
quite the reverse. In an evil day the
malaria mosquito was carried TO the Mauri-
tius, and now the island is full Of them. and
unhealthy. What guar
antee have we that In islands under like
climatic conditions-e. o., FIJI and the
sandwich Islands-a similar calamity may
not occur?
sThis Is the moral would like TO impres
ipon you. Discovery is OF little useJ
Unless II has practical application. The
application Of the dl9oovery
a -. .ho.o 10 Y;o,,a ipaacfa ara tha dia-