Vlll PREFACE 



Nevertheless much has already been accomplished, though it 

 is little to what might be done if more adequate funds were 

 at the disposal of our Colonial Medical and Administrative 

 Authorities. The enlightened policy of the Colonial Office 

 contrasts sadly with the lack of interest displayed by the 

 public as a whole, both at home and in the Colonies affected. 

 Public and private funds could not be directed more profitably 

 to the service of humanity than in the fields which the far- 

 sighted enterprise of this Department has opened up of recent 

 years. 



New and formidable developments in the problem of 

 Sleeping Sickness, to confine ourselves to the second example 

 we have chosen, render it imperative that immediate steps 

 should be taken to combat the spread of a particularly deadly 

 variety of this infection, which, although at present confined 

 to small areas in Nyasaland and the adjoining provinces, 

 threatens to extend over a large part of Africa. 



In addition to these two examples, Malaria in all its forms 

 is gradually becoming subject to human control, though some 

 countries are slow to realize that they cannot remain neutral 

 in this war waged by science against their most deadly internal 

 enemies, the mosquitoes. Verily the fly's proboscis is more 

 successful in retarding the progress of civilization and the 

 alleviation of human suffering than all the armaments of our 

 most Christian Powers ! 



The author's main object in writing this book has been 

 to collocate the more important observations concerning the 

 part taken by biting flies in the transmission of disease. In 

 doing this it seemed advisable to include notes on the classi- 

 fication of the flies concerned and also descriptions of the 

 infections transmitted, but no attempt has been made to give 

 any account of the clinical symptoms of the various diseases, 



