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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of the parasite is a free-living amoeba

10

. Bignami however, while rejecting

Manson’s version of the theory, adopted King’s, and stated that he had even

made some experiments on the subject in 1894; but these were only referred to

as a past event

29

, and seemed to have been quickly abandoned.

It is probable that these writers would have remained indefinitely in this

position but for the researches of others. In 1895-1897, Sacharoff

23

, Simond

35

,

MacCallum

36

, and myself

32 

destroyed the Italian theory regarding the motile

filaments; and then the publications of the 18th December, 1897

38

, the 26th

February, 1898

39

, the 21st May

42

, the 18th June

4I

, the 24th September

43

, and

11th October

46

, completely demonstrated the life-history of this group of para-

sites in mosquitoes; clearly indicated the genus concerned in the propagation

of aestivo-autumnal fever; and gave other details mentioned in section 17.

As all these papers, except those of the 21st May and the 11th October

(which were in fact covered by Manson’s papers of the 18th June and the 24th

September), were published in such a prominent organ as the British Medical

Journal, it is to be assumed that they were from the first known to the Italian

writers, who have always shown a prompt knowledge of the labours of others.

In his first publication

44

, Grassi refers to my work without mentioning my

name or giving references - as if it were then perfectly well-known in Italy.

The later publications of Bignami and Grassi

48

,

47 

show that they were quite

intimate with it before they themselves attained any definite results.

Such being the case, in order to follow my work in Italy and elsewhere, all

that was now needed was to determine the genera of my grey and dappled-

winged mosquitoes from such indications as I had been able to give. The for-

mer had been described in two papers, and was most evidently closely allied to

Culex pipiens; 

and the latter, in which the aestivo-autumnal parasites had been

shown to develop, were described in 1897

38 

as follows:

"The latter are a large brown species biting well in the day-time, and in-

cidentally found to be capable of harbouring the filaria sanguinis hominis. The

back of the thorax and abdomen is a light fawn colour; the lower surface of

the same, and the terminal segments of the body a dark chocolate brown. The

wings are light brown to white, and have four dark spots on the anterior ner-

vure. The haustellum and tarsi are brindled dark and light brown. The eggs -

at least when not properly developed - are shaped curiously like ancient boats

with raised stem and prow, and have lines radiating from the concave border

like banks of oars - so far as I have seen, a unique shape for mosquito’s eggs.

The species appears to belong to a family distinct from the ordinary brindled

and grey insects; but there is an allied species here, only more slender, whiter,

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S

and much less voracious." In the next paper

39 

these small insects also are called

"dappled-winged".

At that time in Italy the Culicidae had been carefully studied by Ficalbi in

several works

31 

, and it was an easy task for anyone possessing these works, and

also having fresh mosquitoes for dissection, to determine the genus of my

dappled-winged mosquitoes from my description alone. Although I did not

give the entomological criterion of the genus Anopheles (the long palpi of the

female), I gave three other details which sufficed for the identification. First,

the dappled-winged mosquitoes belonged to a group distinct from the grey

mosquitoes (Culex pipiens type). Secondly, both species of this group had

spotted wings ; and still more particularly, one of them (certainly) had exactly

"our dark spots on the anterior nervure". Now it is well-known that very

few Culices and Stegomyiae have spotted wings, while Anopheles almost always

have them. The Anopheles, however, not only generally possess spotted wings,

but the spots are generally four in number and arranged along or close to the anterior

nervure. 

Lastly, if any doubt remained the observer would only have to catch

the first spotted-winged female gnat and to examine the eggs within her, when

they would be immediately seen to possess the characteristic boat-like shape,

with the well-known clasping membrane simulating oars on either side.

It is curious that some of those who have written on the subject have over-

looked the fact that the very first Italian mosquito which from its name alone

would be suggested by my description was Anopheles claviger. Two of the

synonyms of this insect are Anopheles quadrimaculatus, Say, and Anopheles ma-

culipennis, 

Meigen!

There is, however, no doubt whatever that the Italians detected the genus

of my dappled-winged mosquitoes, because they themselves say so in two of

their articles of November

48,51 

. Nuttall admits the fact

74

. But there is reason

to suppose that they recognized the insects long before November.

It was evidently Manson’s paper of the 18th June, 1898 which stimulated

the Italians to renewed activity, because they set to work shortly afterwards.

But their success was delayed by efforts towards originality. Grassi endeav-

oured to find the guilty species of mosquito by its prevalence in malarious

localities. His efforts were a close repetition of mine in the Sigur Ghat - even

his servant was attacked by malaria as mine had been. He discovered three

species of guilty mosquito, namely Culex penicillaris, C. malariae (so named by

him - really C. vexans), and Anopheles claviger - principally (per lo meno) the

first

44

. I 

 

have already shown in sections 11

 

and 12 how useless it is to attempt

to identify the malaria-bearing species by its preponderance in malarious

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