Ronald Ross Nobel Lecture

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

99

places; and it has now been demonstrated that even in Italy there is no such rela-

tion between the disease and its agent. Anopheles abound where there is no

malaria - even round Liverpool. Needless to say then, two out of the three

species isolated by Grassi have nothing to do with the disease. He was right

regarding the third, A. claviger; but it is quite reasonable to suppose that he

detached this simply from my description of the dappled-winged mosquitoes.

As a matter of fact all these epidemiological efforts of Grassi, though interest-

ing in a small way, were nothing but a series of vague speculations.*

Meantime Bignami, after four year’s inaction, had returned to his old meth-

od of attempting to infect men by the bites of mosquitoes brought from mala-

rious places. His results are minutely recorded in his paper

48

. He set to work in

August - that is, after Manson had proclaimed at the British Medical Associa-

tion that I had succeeded in infecting birds by the bites of mosquitoes

43

. Big-

nami’s task was now vastly simplified; with the guidance of my work he

collected his mosquitoes from infected houses; whereas if he had continued to

act in accordance with his own theory he would have collected them from

marshes - which would have led to constant failure (section 13). He claimed

his first success early in November, but still could not say which of the various

kinds of mosquitoes employed by him had produced the result.**

Up to November therefore the Italians had failed either to find the guilty

species of mosquito or to demonstrate the life-cycle of the parasite in the in-

sects. At this point Charles’s series of eight letters addressed from Rome to me

(dated from the 4th November to the 14th January) commence. They have

been printed by me with his consent; and show clearly (what however can be

also demonstrated from their own writings) that the Italians were then inti-

mately acquainted with my work; that they had received my report

42 

giving

full details of technique: and that they had detected the genus of my grey mos-

quitoes (from specimens sent by Manson) and of my dappled-winged mos-

quitoes (from my description). In his letter of the 8th November, 1898, Man-

* The writers of some zoological text-books, who have evidently had little personal ex-

perience of the disease, seem to have actually believed that Grassi determined the "Ano-

pheles 

malariferi" by these efforts. That is not the case. In an early work

54

 I said that they

were made independently of Manson and myself; but this was written before I

 

studied

the Italian work with close attention; and since then I have withdrawn the statement

72

.

** That human malaria is conveyed by the bites of mosquitoes had of course been proved

- practically to a certainty - by my infection of numerous birds three months previously.

Bignami’s experiment was merely a formality of which the success could already be fore-

told with confidence. The statement, frequently made, that he was the first to give exper-

imental demonstration of this fact may be set aside without comment.

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100 

  1 9 0 2  R.R OS S

son records having sent some of my preparations to Charles and Bignami (on

or before that date); and Charles in his letter of the 25th November records

showing one of these to Grassi (on or before that date). It is possible, however,

that the Italians had seen my preparations long before this, as numbers of them

had been sent to Manson and Laveran in the spring and summer; and they may

also have seen those of Koch, who had cultivated Proteosoma in Rome in Sep-

tember.

Bignami, Bastianelli, and Grassi had now evidently determined to resort to

the correct method for determining the guilty species of mosquito, and imi-

tated exactly the experiment by which I had ascertained the second host of

Proteosoma 

in the previous March. The experiment was recorded by them on

the 28th November

51

. They fed six Culex pipiens, one Anopheles nigripes and

four Anopheles claviger on some cases of crescents, and at last found my pig-

mented cells in two of the last species. They do not record the exact date on

which this observation was made, but from Charles’s letters it would appear

to have been on the 25th November or later.

This, if correct, was the first definite demonstration of the guilty species of

mosquito in Italy. It was made fifteen months after my original demonstration

of the same parasite in the same genus of mosquitoes in Secunderabad on the

20th August, 1897

38

, and nearly four months after Manson had announced the

whole life-cycle of Proteosoma at the British Medical Association

43

. The Italian

experiment was, however, of doubtful correctness, because the authors do not

state that the mosquitoes used by them had been bred from the larvae

51

. At the

same time they actually impute to me the very fault which they themselves

were committing, and do so contrary to the printed evidence of my own

words.*

In their next paper

53

they claim to have found the various developmental

stages of the aestivo-autumnal parasites in A. claviger caught in houses and

stables, or fed on patients in hospital. Here again, examination of the publica-

tion shows that none of the insects employed seem to have been bred from the

larvae; and, what is still more important, the number of insects on which the

observations were made is not exactly given. For all we know, the whole

paper may have been written on the strength of only a very few positive re-

sults; and this is the more possible because it describes a life-cycle which is an

* They say that my experiment was doubtful because my mosquitoes may have previ-

ously bitten other animals

51

. Now it is clearly stated in my publications* that the insects

used by me had been bred in "bottles from the larvae"; and from the whole tenor of my

researches it was evident that such was the case.

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