63 



I will not dwell upon these points any longer because this work is 

 not exactly concerned so much with the prevention of disease as with 

 the extermination of mosquitoes ; but I shall now give extracts from 

 the descriptions of their own labours, written by several capable 

 workers. These extracts will be found very useful by the reader who 

 wishes to make similar efforts himself. 



The campaigns are described in the order in which they were 

 undertaken, beginning with that of YOUNG and THOMSON and con- 

 cluding with that of the Liverpool School of Tropical Medicine in 

 Sierra Leone. Doubtless many small campaigns have been under- 

 taken by individual medical men. I do not refer to all of these 

 because I do not possess full accounts, or because (in some cases) 

 they were evidently too perfunctory to be worth mentioning. The 

 Havana and Freetown campaigns seem to be the only ones carried 

 out on a large scale and based entirely on the extermination principle. 

 If I have overlooked any work in this line, I hope that those who 

 have done the work will send me details for insertion in future 

 editions. 



An excellent American work on Mosquitoes, by L. O. HOWARD, 

 has just come into my hands when completing the proofs of this work. 

 It contains accounts of several interesting American campaigns. 

 Owing to the shorter summer, the use of oil is likely to be more effica- 

 cious in the temperate parts of the United States than in the tropics. 

 Mr. HOWARD gives many interesting stories of mosquitoes in America, 

 which suggest that the habits of the insects in cooler regions are 

 somewhat different from their habits in the tropics. Of course, cam- 

 paigns against mosquitoes in civilised countries will always be much 

 easier than campaigns in the tropics. 



