Ronald Ross Nobel Lecture

66

   1 9 0 2   R .R OS S

Coccidia 

are not of the nature of flagellated spores at all, but of the nature of

sperms

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. How were these facts to be reconciled?

In a letter dated the 17th November 1897 Manson informed me that a dis-

covery had been made by W. G. MacCallum in America regarding the motile

filaments, showing independently that they are of the nature suggested by

Simond’s work. He did not send me the literature; and as his letter reached

me at Kherwara I could not then obtain it. Shortly after my arrival at Calcutta

however, I procured a copy of the Lancet

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which gave an abstract of Mac-

Callum’s work. The discovery was as follows.

In 1897 MacCallum undertook a study of the motile filaments. Working

with the Halteridium of birds he noticed first that the gametocytes seemed to

be of two kinds, namely one kind which produced the motile filaments, and

another kind which did not do so. On watching two of these cells, one of each

kind in the same field of the microscope, he observed (July 1897) that the fila-

ments escaped from one as usual; that it moved about actively for a time; and

then approaching the other gametocyte actually entered it. Other observa-

tions of MacCallum and Opie, made both on Halteridium and on the cres-

centic gametocytes of the aestivo-autumnal parasite of man, confirmed this

beautiful discovery. The fact, as previously shown by Sacharoff, that the fila-

ments contain chromatin was now explained; and also the facts that they

escape and move about in the blood. They are, indeed, sperms which are emit-

ted from the one kind of gametocytes, the males, and which fertilize the other

kind, the females. Thus these minute parasites, among the lowest of creatures,

have their sexes, and a form of sexual reproduction precisely like that of the

highest animals.

More than this, MacCallum observed in the case of Halteriditim of the crow

that the female cell, motionless before fertilization, afterwards becomes elon-

gated and vigorous, and moves across the field in vitro. This motile form had

apparently long been seen by Danilewski and had been called by him a vermi-

cule.*

So much for the motile filaments, but now what were the pigmented cells?

Everyone seems to have thought that as soon as the flagellate spores disappear-

ed, so did Manson’s theory. But it was not so. The induction remained as

strong as before; the locus of the phenomenon was still in all probability the

* I should certainly have observed these facts when I was making a special study of the

motile filaments in 1895 and 1896. I repeatedly saw them apparently attacking leuco-

cytes

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. The reason why I found that only a percentage of crescents emit the filaments in

the mosquito’s stomach is now explained the remainder were females (section 11).

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stomach-cavity of the mosquito. MacCallum’s work seems to have reached

Manson shortly after my discovery of the pigmented cells came to him. He

connected the two groups of facts in a moment. My pigmented cells were the

vermicules, or fertilized female cells, which had burrowed into the insect’s tissues for the

purpose of undergoing further development there. 

This, and not my hypothesis

made before MacCallum’s paper was known to me, explained the presence of

pigment in the cells. He communicated his views to me in his letter of the 7th

February, and published them later

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.

Meanwhile, after another struggle, I was again in sight of the pigmented

cells. On my arrival at Calcutta I found myself installed in the convenient little

laboratory which had been formerly used by Professor D. D. Cunningham.

There was a native assistant there; but I hired at my own expense several oth-

ers, especially a most intelligent Mahommedan named Mahommed Bux, who

after he had been trained showed great enthusiasm and gave me much assist-

ance. To my delight I at once noted several varieties of dappled-winged mos-

quitoes, besides many kinds of grey and brindled mosquitoes, actually within

the laboratory, and found the breeding-places of the latter just outside. Those

of the dappled-winged mosquitoes were detected a little later; and were again

seen to be pools of water on the ground. The next thing was to obtain cases of

malaria; but here I was met by an unexpected and most unforeseen misfor-

tune. The plague had been raging all this time in India; and on the Govern-

ment’s trying to introduce Haffkine’s prophylactic inoculation in Calcutta

just before my arrival, serious riots, during which many of the Europeans had

felt themselves obliged to go about armed with revolvers, had occurred. The

ignorant populace, thinking that the British were trying to inoculate them

with and not against plague, flew into paroxysms of terror at the very sight of

a European hakim (physician), while anything remotely resembling inocula-

tion made them frantic. The physicians of the Calcutta hospitals were evident-

ly very unwilling that I should use their cases for my experiments under these

circumstances; and, as I had no hospital of my own as in Secunderabad and

Bangalore, I was forced to send my assistants into the bazaar (native parts of

the city) in order to try to induce patients to come to me on payment. Calcutta

is not very malarious, especially at that time of the year, and it was only on

large payment that several beggars with fever were induced to come to me;

but when I proposed to prick their fingers in order to examine their blood

they generally left their money, took up their crutches, and fled without a

word! This placed me in complete perplexity as to what to do, until I remem-

bered the malaria of birds. A number of crows, pigeons, weaver-birds, spar-

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