NA TURE 



[May 6, 1922 



to the proof and found that it corresponded with fact : 

 the microfilariae were sucked into the stomach of his 

 mosquitoes, and some of them migrated into the insects' 

 tissues and there underwent definite changes of growth 

 and development, and were thus set on their course, 

 via the infected mosquito, for infecting other human 

 beings. 



It must be borne in mind that Manson was. a busy- 

 medical practitioner working, far off and alone, as he 

 could find time, and without particular appliances. 

 It is not surprising, therefore, that he did not follow 

 the exact course taken by infected mosquitoes in trans- 

 ferring their infection to man. He was content to 

 have demonstrated the essential realities of a great 

 original conception, and to have established the great 

 pathogenetic discovery — so pregnant with further pos- 

 sibilities of "knowledge, so abundant in its practical 

 appUcations to human welfare — that a common blood- 

 sucking insect is the essential J actor in the maintenance 

 and dissemination of a widely-diffused parasitic disease. 



In 1894, when he had left China, Manson found his 

 opportunity of applying this great principle to the 

 problem of malarial infection. He had followed all 

 the work that had been done on the parasites of malaria 

 since their discovery by Laveran in 1880, and he had 

 come to the conclusion that the secret lay in the motile 

 filaments extruded from forms of the parasite now 

 known to be male gametocytes. Other observers re- 

 garded these filaments as degenerations : Manson inter- 

 preted them in the light of his filaria observations. 

 He argued that as the forms that produce them are 

 so persistent and resistant, the filaments must have 

 some vital meaning ; that since they are not produced 

 until the blood has been shed, their destiny lies in the 

 outside world ; and that since they cannot get out 

 spontaneously, they possibly are extracted and nursed 

 — like the microfilarise — by mosquitoes. This is Man- 

 son's mosquito-malaria theory, that inspired and guided 

 Ross in his wonderful discovery of the sexual cycle of 

 the malaria parasite and final solution of the problem 

 of malarial infection. The theory has sometimes been 

 referred to as if it were one of the several ingenious 

 speculations that have attributed the spread of malarial 

 fevers to mosquitoes : quite otherwise ; it stands apart 

 as a closely-reasoned working hypothesis based on 

 known facts in the history of the malaria parasite and 

 legitimate inferences from the history of Filaria ban- 

 crqfti. Ross, writing with all the combined authority 

 of an historian and a malariologist, says of it (Nature, 

 vol. 61, 1900, p. 523) : " Manson's theory was what I 

 have called it — an induction — a chain of reasoning from 

 which it was impossible to escape. ... I have no hesita- 

 tion in saying that it was Manson's theory, and no 

 other, which actually solved the problem ; and, to be 

 frank, I am equally certain that but for Manson's 

 theory the problem would have remained unsolved at 

 the present day." 



Manson had retired from China in 1890 and settled 

 in London. In 1894 he joined the staff of the Seamen's 

 Hospital, and in 1897 was appointed Medical Adviser 

 to the Colonial Ofhce. He was now able to realise his 

 hfelong dream of a school in London where medical 

 men going to the tropics could acquire all the necessary 

 craftsmanship that he himself had yearned after in his 

 early days in China. In this design he happily ob- 



NO. 2740, VOL. 109] 



tained the countenance of Joseph Chamberlain and the 

 co-operation of the Seamen's Hospital Society, and in 

 1899 the London School of Tropical Medicine was 

 established under him at the Albert Dock. Here, until 

 his retirement from all active practice in 1913, he 

 radiated rather than imparted wisdom and inspiration 

 to many hundreds of his younger professional brethren ; 

 and here, under his sage and benign influence, there 

 grew up a sort of Mansonian tradition that for useful 

 work in the tropics a medical man, though always a 

 clinician at heart and a sanitarian in his general out- 

 look, must be a biologist in his attitude to pathology 

 and aetiology. 



Manson's place in the history of medicine can be 

 estimated only when we consider how much of what for 

 convenience we speak of as " tropical disease " is due 

 to animal and animalcule parasites, and to what extent 

 those parasites are fostered and diffused by blood- 

 sucking arthropoda. Men before Manson had specu- 

 lated on the pathogenetic possibilities — or even proba- 

 bihties — of predaceous insects, but no man before 

 him had followed — or gone near following — a specific 

 pathogenic organism into a specific predaceous arthro- 

 pod and discovered what happened to it there. " The 

 light of humane minds," says Hobbes, " is perspicuous 

 words, by exact definition snuffed and purged from 

 ambiguity " : it is Manson's pre-eminent distinction 

 to have been the first to discover a connected series 

 of facts and to have recorded them in exact definitions 

 purged and snuffed from ambiguity — which is the 

 acquisition of science. With Manson's high achieve- 

 ments as an original investigator and a teacher we 

 have to consider also his extraordinary influence as a 

 most prescient clinician — and a clinician who never 

 forgot the comfort of his patients : in all this, as in 

 his large humanity and his benevolent attitude to his 

 fellow-workers, he worthily upheld the ideal of Hippo- 

 crates ; and I have often thought that, as the Father 

 of Tropical Medicine, his name may, perhaps, have the 

 same lasting fragrance as that of his immortal arche- 

 type. 



A. A. 



Sir a. B. Kempe, F.R.S. 



Sir Alfred Bray Kempe, whose death occurred on 

 April 21, was born in 1849, ^'^^ educated at St. Paul's 

 School and at Cambridge, where he was twenty-second 

 Wrangler. His first contribution to the science of 

 mathematics was in 1876, when, in a paper on a general 

 method of describing curves of the nth. degree by 

 link-work, he laid the foundation of the excellent dis- 

 coveries he was destined to make in " linkages " — a 

 subject in which he took a lifelong interest. In 1877 

 he gave his well-known lecture, " How to draw a 

 straight line," in which he traced the history of the 

 connection between the straight line and linkages from 

 the partially successful attempts of Watt, Richard 

 Roberts, and Tchebicheff, to the practical solution of 

 the problem by Peaucellier in 1864. Together with 

 Hart of Woolwich Academy and Sylvester he had added 

 much to the knowledge of the subject, and these addi- 

 tions he described with models. 



A paper on conjugate 4-piece hnkages followed in 

 1878, and some smaller papers, but Kempe's principal 



