47 



is~a eountrv full of waterways and canals, and the tilling up of drains, 

 which are essential to the plantations, is impossible ; the alternative 

 appeared to be Cjuinine, which was the policy adopted. Here the 

 spleen rates were high in comparison with the death rates, but clearly 

 75 per cent, of the malarial problem in British Guiana is already solved 

 and the way to eradicate the disease is by Anopheline reduction. 

 In Barbados the author thinks that the absence of breeding places 

 is the reason for the absence of malaria, rather than the presence of 

 " Millions." In all cases it would seem that drainage indicates the 

 way to overcome the disease. 



In the discussion which followed Sir Ronald Ross expressed agree- 

 ment with the methods advocated by Dr. Malcolm Watson, and referred 

 to his own work on the extermination of malaria in India, where he used 

 precisely the same method, the report of which was published in the 

 Indian Medical Gazette for July 1899. Sir R. Ross also stated that 

 quinine as a preventive has distracted attention from the fundamental 

 method and expressed doubts whether quinine is really cheaper for 

 the benefits given than is mosquito reduction. Dr. D. Thomson 

 was of opinion that after the difficult work done in the Malay States 

 it ought to be quite possible, by clearing the jungle, to reduce mosquitos 

 in all the settlements at the mouth of the Niger. Dr. Andrew Balfour, 

 referring to a letter from Mr. Sawer working in the Sudan, says that 

 the results obtained by drainage in that country speak well for that 

 method. Here the drains are deep, and graded drainage channels 

 cut into the soil and undoubtedly benefit agriculture at the same time. 

 The statement made by Dr. Watson that the absence of malaria in 

 Barbados was due probably to the absence of suitable breeding places 

 was criticised by Dr. G. C. Low, who stated that he found permanent 

 collections of water formine: swamps, especially near Worthing, about 

 three miles from the capital of the island. From water taken from 

 these swamps to St. Vincent, a neighbouring island, A. alhipes and 

 argyrotarsis (the West Indian malarial-carriers) were reared with ease. 

 The isolation of the island, the situation of the suitable collections of 

 water away from the harbour and main town, and the difficulty of 

 mosquitos getting ashore from the ships which lie in an open roadstead 

 a mile or more from shore, were considered by Dr. Low to be the chief 

 factors dominating the absence of these insects ; he agreed that the 

 Barbados " millions " were not the cause. Dr. Low also stated that he 

 has found aJbimanus breeding in running water. Dr. Bahr stated that 

 in Ceylon malaria is essentially a disease of the low country, especially 

 of the rice districts. Here A. culicifacies is the chief carrier; 

 A. macidatus was encountered once in a swift flowing stream. 

 A. albirostris, contrary to the experience of Dr. Malcolm Watson in 

 Malaya, breeds in the muddy parts of paddy-fields. To a less extent 

 malaria is a disease of the jungle in Ceylon. The problem of the 

 abolition of the paddy-field is one of importance to the Colony and 

 Dr. Bahr thinks that paddy-fields in the vicinity of towns should be 

 abohshed. He also suggested that the reason why a mosquito will 

 transmit a parasite in one place and apparently fail to do so in another 

 ought to be more fully investigated. The President, Sir R. H. Charles, 

 stated that there is no question that improvement in agriculture is one 

 of the most necessary works against malaria. In India this is a difficult 

 task and village sanitation is at the root of the whole matter. Atten- 



