234 Transactions. — Miscellaneous. 



arguments (fallacious ones) against the theory of the implica- 

 tion of mosquitos as agents in the propagation of fever. 

 For this the indefiniteness of the term "mosquito" was in 

 large part responsible. The medical and lay press were inun- 

 dated with letters, more especially from retired officials, who 

 asserted that they had lived for years in mosquito-infested 

 regions and had not had malaria. These individuals had not 

 taken into consideration the fact that a special mosquito was 

 required. Some asserted that malaria had arisen where no 

 mosquitos were to be found, but in most of these instances 

 a proper investigation led to the finding of Anopheles. 



The occurrence of cases at sea was brought forward as 

 another argument against the theory, but here the explana- 

 tion was readily forthcoming. The period of development 

 after the mosquito injects the parasite lasts some twelve to 

 fourteen days, and the period allows the infected individual 

 to travel a long distance. An instance of this occurred on 

 a steamer which, after leaving Calcutta, anchored for a night 

 in the delta of the Ganges. She called only at Colombo, and 

 three or four days after leaving that port there was a general 

 outbreak of ague. The time was about fourteen days from 

 the Ganges, showing, as we now know, that the infection had 

 taken place in that river. 



Although the scientific proof of the mosquito theory was 

 complete, something further was needed to impress the fact 

 upon the mass of those living in malarious districts, and per- 

 haps more especially on lay officials responsible for the sani- 

 tation of tropical colonies. To do this, experiments of a 

 somewhat sensational character were carried out in several 

 countoes. I will refer only to those for which British 

 workers were responsible. One of those experiments con- 

 sisted in the rearing of Anopheles in Eome from the larvae, 

 and allowing the adult female mosquito thus reared to feed on 

 a malarial patient in a Roman hospital. For the purpose a 

 case of a mild type was chosen. The mosquitos thus fed 

 were forwarded, carefully packed, to London, and allowed to 

 have another meal from voluntary victims — medical men — one 

 of whom was a son of Dr. Manson. the originator of the 

 mosquito theory. These London volunteers in due course 

 developed malaria of the same type as the patient in Rome 

 who had afforded the mosquitos their first meal. 



A second experiment was undertaken by some medical 

 men connected with the London School of Tropical Medicine. 

 Their ability to make it was largely due to the Colonial Secre- 

 tary, Mr. Chamberlain, who appreciated its value in relation 

 to colonial development. The experiment consisted in build- 

 ing a mosquito-proof house specially designed to be suitable 

 for British officials iu malarious countries, well ventilated, 



