CHAP. XX. | INSECTS AND DISEASE. 1 77 



Chapter XX. 

 INSECTS AND DISEASE. 



" Rii 



/// Memoriam. 



" As when .1 swarme of gnats al eventide 

 1 )ut of ihe fennes of Allan doe arise. 

 Their murmuring small trumpets sownden wide, 

 Whiles in the air their clust'ring army Hies. 

 That as a cloud doth seem t" dim the skies . 

 Xe man nor beast may rest '.r take repasl 



heir sharp wounds and noyous injuries. 

 Till the lierce northern wind with blust'ring blast 

 blo« them (|uite away, and in the ocean 



Faery Queen. 



TWENTY or more years ago a man who seriously devoted his time 

 to the study of insects such as mosquitos would have been regarded 

 almost universally as a triflcr who was wasting his time with little 

 benefit to himself and none at all to anyone else. At the present 

 time no one with any pretensions to possession of medical or 

 sanitary knowledge can afford to disregard the study of this group 

 of apparently insignificant insects. The extension of their study 

 in India alone may be gauged roughly by comparison of these two 

 facts, that twenty years ago only four different species of mosquitos 

 were known to occur in the Indian Region whereas to-day we know 

 of upwards of two hundred different kinds and have at our disposal 

 elaborate monograph> regarding their structure, lifehistories anil 

 habits, whilst every year set •- the issue of more comprehensive and 

 detailed publications on these insects and others of a similar im- 

 portance. It is not because of their intrinsic beauty or commercial 

 value that such a cult has suddenly arisen but solely on account of 

 the recognition of the fact that certain mosquitos are responsible 

 for the occurrence in man of various diseases, of which malaria is 

 to-day probably the most important in India. A- its name implies, 

 malaria was for long supposed to be due directly to the inhalation 

 of poisonous exudations from marshy places, but it is now certain, 

 as the result of prolonged and careful experiments, that the real 

 connection of marshy places and malaria is that pools and other 

 collections of water serve as breeding-grounds for certain kinds of 

 mosquitos which carry the malarial parasite. 



It iv not too much to say that the discovery of the fact for it is 

 no longer a men' theory of the trans by the 



\2 



