Ronald Ross Nobel Lecture

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

95

"The fact that malaria, when it occurs epidemically, is often confined al-

most entirely to the children, the adults remaining free and therefore having

become immune, I discovered first in villages in Java which lie in the valley of

Ambarawa. That was at the beginning of November 1899. I reported on it on

the 9th of December 1899, and my letter was published in the Deutsche Medi-

zinische Wochenschrift, 

No. 5, 1900, beginning of February. I obtained my first,

successful cultivation of Proteosoma in mosquitoes in company of Prof. R.

Pfeiffer in Rome in September 1898. We continued the investigation in Ber-

lin; and in the middle of November we followed the developmental stages of

the parasite up to the sickle-shaped bodies in the poison glands of the mosqui-

to - that is up to the end. We were able to determine the form of Würmchen

(vermicule) in Proteosoma so easily because I, with Professor Kossel, had al-

ready in June of the same year (1898), without knowledge of MacCallum’s

investigation, detected the origin of the spermatozoa, the process of fertiliza-

tion, and the formation of the Würmchen in Halteridium.

"The publication of this investigation was very much delayed in conse-

quence of the long time taken for the reproduction of the photographs in a

way which satisfied me.

"At all events I have not thought it necessary to attempt to assert my priority

on this occasion as the matter concerned only the confirmation of already

known things."

Professor Koch has the honour of having been one of the first, not only in-

dependently to conceive the mosquito theory of malaria, but also to attack it

by experiment. He and Kossel independently observed the function of the

motile filaments by the employment of correct methods of staining: this is

practically admitted by Bignami (Lancet, 2 (1898), p. 1898) who was later able,

probably through his instruction, to demonstrate the chromatin in the motile

filaments

50

 - a thing which he had refused to credit before. Koch also was the

first to fill a gap in my own researches on Proteosoma by demonstrating the

passage of the vermicule through the wall of the mosquito’s stomach - a sub-

ject in which Grassi merely followed him later. That he succeeded in culti-

vating Proteosoma in Rome and Berlin, in September to November, 1898,

shows that he was the first to confirm my own observations. About that time

Dr. Annett of the Liverpool School of Tropical Medicine saw some of his prep-

arations of pigmented cells in Berlin. Koch’s discovery of the frequent infec-

tion in native children in the tropics was one which I had entirely failed to

make - although I should have made it; and is an addition to our knowledge of

the very highest importance, being of far greater intrinsic value than much of

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96

 

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the trifling matter which has been put forward in other quarters with much

réclame. 

It enables us to explain with ease the source of most malarial infections

in the tropics, and, besides, gives a complete revelation regarding the possibil-

ity of immunity in malaria, a thing in which no one would previously believe.

Added to this Professor Koch has pressed still further onwards, and pushed

with authority and ability the great subject of the practical prevention of the

disease in the tropics - a matter the importance of which few writers on the

subject have seemed able to comprehend. The methods recommended by me

consist principally of the use of mosquito-nets and the extirpation of mosqui-

toes; but Koch at once inaugurated a new conception which had not occurred

to me and which consisted in the cinchonization of the people in malarious

localities. Although this measure is not always possible in its full extent, still

experience shows that in a modified form it is most useful; and I have come to

the conclusion that it should always be enforced as much as practicable in addi-

tion to the measures which I advocate. It was also Koch who was the first to

call general attention to the important fact that a sudden and ill-advised dose

of quinine is apt to precipitate attacks of blackwater fever in certain persons

and localities.*

(2). Many erroneous ideas have been formed about the Italian work (re-

ferred to in section 20) by those who have no practical knowledge of malaria

or full acquaintance with the literature. The facts are exactly as follows.

The South of Italy affords unparalleled advantages for the study of malaria,

because abundance of material is there combined with great facilities in connec-

tion with laboratories, literature, and scientific communion; hence, though the

principal discoveries have been made elsewhere, the writers of Southern Italy

have been able to add to them much detail, which has proved more or less

correct. It was hoped after Laveran’s discovery that they would be able to find

the extracorporeal phase of the parasite; but, unfortunately, misled by fond-

ness for hypotheses, they fell into fundamental errors. Most of them hastily

concluded that the motile filaments are "agony-forms"; and, as described in

sections 6 and 11, A. Bignami rejected Manson’s induction on this account;

and another writer, G.B. Grassi, abandoned the whole mosquito theory (1)

because mosquitoes do not bite birds, (2) because they abound in places where

there is no malaria, and (3) because the malaria parasites die in the stomachs

of mosquitoes. At the same time he maintained that the extracorporeal stage

* I should like to add, in contradiction of many inaccurate statements which have been

made, that his acknowledgment of my own observations has been the most complete

possible.

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