Ronald Ross Nobel Lecture

    R E S E A R C H E S   O N   M A L A R I A

47

duction) and possibly also from other mosquitoes, and then communicate the

parasites to healthy persons - perhaps by inoculation. It will be seen which

view is right; but in consequence of my negative experiments, the inoculation

theory was not much favoured by me until I made my researches in the Sigur

Ghat (section 12).

My duties at Bangalore continued for a year and a half At first placed upon

special duty to report on the sanitation of the town (80,000 inhabitants), I was

afterwards appointed officiating Residency Surgeon there and was required

to reorganize the whole of the sanitary arrangements, to create a health de-

partment, to participate in a committee designated to reconstruct the munici-

pal regulations, and to contend against several outbreaks of cholera. Conse-

quently I did not possess as much time as at Secunderabad for my researches

on malaria, but nevertheless in addition to the experiments last referred to,

I was able to dissect many hundreds of mosquitoes in pursuance of my princi-

pal plan of campaign. Several agents were employed to collect the larvae of as

many kinds of mosquitoes as possible, especially from several spots whence

most of the cases of fever came; and these insects, belonging to many species

of the brindled and grey groups of mosquitoes,* were all tested by direct

feeding on cases of malaria, especially aestivo-autunmal. But though each

insect was examined with the utmost care, almost every cell being scrupulous-

ly searched for parasites, the results still remained entirely negative.

Towards the end of my stay in Bangalore, as failure followed failure, I was

naturally forced to reconsider the whole basis of my work. But no; the most

critical examination of Manson’s induction failed to exhibit any flaw in the

fundamental reasoning. The gametocytes, and the process by which the mo-

tile filaments escape from them after the blood is drawn from the patient,

could only be meant for infection of the mosquito. There was no other ex-

planation. Nature does not create these complex phenomena for nothing; and

the theory must be - was - sound. What then was the cause of my repeated

failures? Was it possible that the kinds of mosquitoes which I had tested hith-

erto - very many kinds - were all of the wrong species?

The reasons for and against this view were as follows. In all the districts and

towns of India in which I had served or stayed during fifteen years - Madras,

Bangalore, Moulmein, the Andamans, Secunderabad, Upper Burma, Bom-

bay, Poona, Calcutta, Karachi, Quetta, the Nilgherry Hills, malaria was un-

doubtedly present, especially among the natives ; and in all of them without

* Not once as yet had I come across the dappled-winged mosquitoes ; though, be it noted,

many of my larvae were collected from ditches and the edges of ponds.

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exception I remember to have noticed mosquitoes belonging to both the grey

and the brindled classes. This naturally suggested a connection between the

disease and the insects; but, on the other hand, were not the later perhaps too

common? So far as I could ascertain, the disease was generally limited to cer-

tain spots and localities (by no means always near marshes); whereas the in-

sects were everywhere, and were indeed often commonest at points were ma-

laria was rare, as in the houses of Europeans. After all may not the true malaria-

bearing variety or varieties have been overlooked by me? Possibly they were

comparatively rare species, or species occurring only at a certain season - a

hypothesis favoured by the well-known fact of the seasonal variation of ma-

laria. Now, as I was fully aware at the time, malarial fever is a relapsing disease

in which attacks continue to occur for years after infection; so that it does not

follow by any means that the infective variety of mosquito must always be

present in a locality, even though numerous cases of malarial fever are present.

And it was to be specially noted that most of the cases occurring in Bangalore

were probably only cases of relapse.

These arguments were not strong enough to be conclusive on either side of

the question. I had done quite right in spending so much time over the grey

and brindled mosquitoes; there was enough prima facie evidence against them

to demand a full enquiry. But before spending more time over them it was

now advisable to see whether further light could be obtained by epidemiolog-

ical investigation. The towns in which I had worked hitherto could scarcely

be considered more than moderately malarious; I now proposed to visit an

intensely malarious spot, at the height, too, of the malarious season in order

to ascertain what kind of mosquitoes prevailed there at the time; and reason-

ably hoped that this kind would prove to be the guilty species.

Being a servant of Government I could not of course go where I pleased

without leave, and I therefore first attempted to interest Government in my

work. Owing to my representations, the United Planters’ Association of

Southern India took up the matter; and the Honourable Mr. Bliss, Member of

Council of the Madras Government, and also Surgeon General Sibthorpe,

head of the Madras Medical Service, were kind enough to give their warm

assistance - for which I shall always be much indebted. The result was that the

Government of Madras made a proposal to the Government of India that I

should now be placed on special duty to investigate malaria. Most unfortu-

nately, however, in addition to the plague, the Afridi war broke out just about

that time, and owing to the paucity of medical officers the Government of

India was obliged to reject the proposal - May 1896. But in the meantime I

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