Ronald Ross Nobel Lecture

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

91

Museum. I found that, as I had already partially learnt through Charles, my

dappled-winged mosquitoes were those of Meigen’s genus Anopheles and that

both my grey and brindled mosquitoes belonged to the same genus, namely

Culex. 

I was dissatisfied with this because it seemed to me certain that they

were of different genera. Recently Theobald in his fine work on mosquitoes

75

has separated them, placing the brindled mosquitoes in the genus Stegomyia,

and reserving the name Culex for the grey mosquitoes. Later, Giles deter-

mined that the grey mosquitoes which carry Proteosoma are Culex fatigans, and

called the large negative dappled-winged mosquitoes of Calcutta Anopheles

rossi.*

Meanwhile Manson had been urging his great scheme of creating special

schools for the teaching of tropical medicine, and had now received the sup-

port of Mr. Chamberlain. In Liverpool, Sir Alfred Jones, supported by Pro-

fessor Boyce of University College, Mr. Adamson, Chairman of the Royal

Southern Hospital, and many other gentlemen, had warmly taken up the

scheme, and now appointed me the first lecturer of the Liverpool School of

Tropical Medicine. I therefore found myself no longer an isolated worker, but

a member of a company determined to advance the interests of life and health

in the tropics. And it was an auspicious moment; for the great weapon which

had just been forged for the prevention of the most important of tropical

diseases needed strong hands to lift and wield it.

Almost my first care on returning to England was to consult eminent zool-

ogists regarding the proper nomenclature for use in connection with the de-

velopmental stages of the parasites in mosquitoes. With the aid of Professor

Herdman I published a paper on the subject

59

, in which, abandoning the hasty

provisional nomenclature hitherto used by me, I called the motile filaments,

microgametes; 

the pigmented cells, zygotes; and the thread-like bodies, blasts.

I also suggested a classification for the parasites of men and of birds. But there

is still great divergence of opinion on these subjects.

Evidently West Africa, a rich and enormous country hitherto paralysed by

malaria, was destined to be the first objective. I lost no time in urging the ad-

visability of sending me there in order to complete my studies of the disease

and determine its agents on the spot. In July I delivered my inaugural lecture

and demanded attention for my scheme for extirpating malaria by attacking

the pool-breeding mosquitoes

5 8

. At the end of July 1899, accompanied by

Mr. E. E. Austen of the British Museum and Dr. H. E. Annet, Demonstrator

* Owing to an error he thought that it was this kind in which I had first found the pig-

mented cells in 1897.

---

92

    1 9 0 2  R.R OS S

of the Liverpool School of Tropical Medicine, I left England for Freetown,

Sierra Leone.

22. Sierra Leone (August-September, 1899). The investigation completed. We

have now reached the last chapter of this history - which I fear has become

tedious. If a literary simile may be allowed in a scientific narrative, I had at

last come to my Ithaca, after many mischances sent by many opposing deities.

Two years had elapsed since I had seen the pigmented cells of the human para-

sites - two years of fruitless efforts, interruptions and bad fortune; and seven

years had elapsed since I had commenced the special study of malaria; but now

assisted by my able colleagues and myself, I needed but a week or two to dem-

onstrate all the stages of the human parasites in dappled-winged mosquitoes,

and also to ascertain the fundamental principles upon which State sanitation

against tropical malaria should be based. I will be brief; the details are given in

the publications

60,67

.

On the day after landing (10th August) we found two species of dappled-

winged mosquitoes (Anopheles costalis, Loew, and Anopheles funestus, Giles) in

abundance. On the 13th August, we detected a pigmented cell, evidently of

the mild tertian parasite, in one of them. A few days later, in some barracks

there was much malaria, we ascertained that a quarter of the mosquitoes (al-

most exclusively A. costalis) were infected; and found in them pigmented cells

evidently derived from all three varieties of parasites - quartan, tertian and

aestivo-autumnal. We also made a few formal feeding experiments, and could

have made as many more as we pleased. The material was unlimited; but our

time was short, and the proof was already sufficient.

We then investigated the conditions under which the Anopheles breed and

propagate malaria. It was the rainy season and the place was full of stagnant

pools. Everywhere the larvae of the dappled-winged mosquitoes were in these

pools, while those of the grey and brindled mosquitoes occurred in tubs and

pots. The great law of malaria - its connection with stagnant water on the

ground - was explained. Moreover, simply by noting the presence of the lar-

vae, we could tell at a glance which pools were dangerous to health and should

be dealt with in the public interests.

The habits of the insects were noted and found to be precisely similar to

those of the Indian species. We studied particularly the characteristic attitude

of the larvae and adults of the dappled-winged mosquitoes, as formerly ob-

served in India - invaluable tests for the immediate and easy recognition of the

agents of the disease; we noted the evidence demonstrating the short flight of

---