Ronald Ross Nobel Lecture

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

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tion of my own labours. For several years afterwards, however, nearly all my

work was credited to these writers.

One interesting fact, however, I learnt from the Italians through Charles,

namely that my grey mosquitoes belonged to the genus Culex and my dap-

pled-winged mosquitoes to the genus Anopheles. Manson appears to have

sent some of the former to Grassi, and, according to Charles’s letters of the

19th November, he thought they were Culex pipiens - as a matter of fact they

were C. fatigans. Also from Charles’s letter of the 25th November and from

their own publications

4 8 , 5 1 

, it was clear that the Italians thought that my dap-

pled-winged mosquitoes were Anopheles claviger; and in his letter of the 6th

January it was stated that Grassi considered some dappled-winged mosquitoes

which I sent him were A. pictus - they were really A. rossi, Giles. I satisfied

myself more fully next year at the British Museum regarding the zoological

names of the mosquitoes studied by me. The Italians had no difficulties in these

respects as they had Ficalbi’s works on gnats to guide them. They received

some more of my preparations, through Dr. Charles, early in January 1899.

On the 22nd December Dr. Daniels, of the Medical Service of British Gui-

ana, arrived. Though somewhat sceptical at first, he was soon convinced after

seeing my preparations and repeating the experiments with care; and he fully

confirmed my work in a paper, which however was not published by the

Royal Society until much later

7 1

. I am much indebted to him for his assistance

and advice in connection with my report on kala-azar - no one has a profound-

er knowledge or a larger experience of malaria. In the time remaining to us we

attempted several series of experiments on human malaria (cases now being

more obtainable), mostly with the large brown dappled-winged mosquito of

Calcutta with which I had made most of my few but negative experiments

recently in Calcutta and Assam. These too proved to be negative. We ascribed

our failure to some mistake; but the cause was ill-fortune. The mosquitoes

were chiefly Anopheles rossi which in Bengal certainly do not easily take ma-

laria.*

* It was, of course, the cold weather in Calcutta, but Daniels and I used incubators. Ste-

phens and Christophers later obtained positive results in Nagpur with A. rossi, but only

by very careful artificial regulation of the temperature

71

.

It should be clearly understood that all my experiments on human malaria since 1897

were made under very unfavourable circumstances, and that I never considered my nega-

tive results to be at all final.

At this time I informed Daniels of some other details; and, in view of a controversy

which arose later, he has kindly testified to this fact in the following letter:

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Several distinguished visitors came to us at this time, F. Plehn, A. E. Wright

and A. Ruffer. They all accepted our work, except the "black spores" men-

tioned in section 17. Nevertheless Daniels and I did not think it right to

abandon them without clear evidence; but when, later, I found closely similar

bodies in large numbers in mosquitoes which had not been infected at all, my

faith was shaken; and it was disturbed still more when I failed to find them in

the infected mosquitoes of Sierra Leone. My doubts were mentioned in the

concluding sentences of my report on kala-azar.

That report was finished on the 30th January

79

, and contains eighty-one

closely printed folio pages. My years’ special duty was now almost finished;

but I could obtain no definite assurance from my chief that I was to be retained

on the same duty for an extended period. Yet the matter was vital to me.

Nearly all the money at my disposal had been spent in consequence of these

researches, chiefly because of the expenses connected with the constant changes

[footnote continued from p. 87]

Dear Ross,

October 8th, 1900.

I shall have great pleasure in testifying to the following facts :

(

I

) Shortly after my arrival in Calcutta in December, 1898, you showed me living

specimens of your "grey", "brindled", and "dappled-winged" mosquitoes.

You pointed out to me the attitude assumed by the last, the position of its larvae in wa-

ter, and the peculiarities of its eggs.

Since then I have learnt that these are characteristics of the genus Anopheles.

You contrasted these with the eggs and larvae of other mosquitoes, which I now know

to belong to the genus Culex.

(2) You showed me two species of "dappled-winged" mosquitoes, and I sent speci-

mens of them to the British Museum where they now are. They have been described by

Major Giles, I. M. S., as Anopheles.

You also showed me a specimen of a stomach of a mosquito with what are now known

as "zygotes". This you stated was the stomach of a "dappled-winged" mosquito, similar

to those you had shown me, which had been fed on a patient with crescents in 1897.

(3) I may add that the development of Proteosoma, as demonstrated to me by you in

the "grey" mosquito, is essentially the same as the development of "crescents" in Anophe-

les 

as observed by me in British Central Africa.

I am, Yours very truly,

C.W.Daniels.

P.S. As regards breeding-places, you informed me that the "dappled-winged" mos-

quitoes breed in puddles, the "brindled" mosquitoes generally in flower-pots, and the

"grey" mosquitoes in tanks, ditches, etc.

Major R. Ross.

C.W.Daniels.

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