REPRODUCTIVE PHASES 141 



that we have just seen that, should it get out, certain 

 cells undergo a further development and produce 

 mobile filaments. It occurred to many that these 

 filaments might be spores, which were in some way 

 carried into the blood of man. Later research showed 

 that this is not their true meaning ; but, acting on some 

 such belief, Dr. Patrick Manson propounded the hypo- 

 thesis that the spores may be conveyed to man by the 

 intervention of some blood-sucking insect ; and the 

 brilliant and laborious researches of Major Ross, 

 undertaken with the view of establishing the truth 

 or falsehood of this hypothesis, have within the last 

 few years cleared up the whole question of the trans- 

 mission of the disease from one patient to another. 



It is a well-established belief in many malarious 

 countries that the mosquito plays a part in the infec- 

 tion. The negroes of the Usambara Mountains, who 

 acquire the disease when they descend to the plains, 

 even use the same word to denote the disease and the 

 mosquito. In Assam, in Italy, and in Southern Tyrol, 

 the belief in the mosquito origin of malaria obtains. 

 Experienced travellers, like Livingstone, Emin Pasha, 

 and General Gordon, insisted on the importance of 

 mosquito-nets, thinking that the netting 'acted as a 

 filter against the malarial poison,' and knowing by 

 experience that its presence diminished the tendency 

 to the disease. The whole epidemiological evidence 

 was put together in a masterly essay on the mosquito 

 theory, read before the Philosophical Society of 

 Washington in 1883, by Professor A. F. A. King. 

 There was thus a considerable body of opinion in 

 favour of the mosquito-malaria theory, when, in 1894, 

 Manson explained his views to Major Ross, at that 

 time a surgeon in the Indian Medical Service. 



Manson's own epoch-making researches on Filaria 

 another human parasite whose intermediate host is the 

 mosquito no doubt strengthened his faith and helped 



