AGENTS OF DISEASE 271 



possessions. Already, thanks to the magnifi- 

 cent work of Sir Patrick Manson, Colonel 

 Bruce, Major Ross, the London and Liverpool 

 Schools of Tropical Medicine, and the Lister 

 Institute, much has been done to safeguard the 

 lives of those Britons whose duties call them to 

 the fever-haunted and malarial lowlands of the 

 tropics. But much still remains to be accom- 

 plished, and it is only by the more general 

 increase of modern scientific methods of obser- 

 vation and investigation that effective results 

 will be obtained. 



That insects have actually played a very 

 important part in the past history of the 

 peoples of the Old World, and that they un- 

 doubtedly acted as subtle factors in the downfall 

 of the great civilizations of Greece and Rome, 

 sounds strange and almost like a fairy tale, and 

 yet the evidence brought together by recent 

 biological and antiquarian research, points to 

 such having been the case. It would be impos- 

 sible, in the space at present at my command, to 

 deal fully with this most intensely interesting 

 subject, and I must therefore give but a short 

 outline sketch. Those of my readers who 

 desire to obtain a deeper insight into this fasci- 

 nating subject will find it most clearly and ably 

 set forth in the pages of Mr. W. H. S. Jones' 

 little book entitled " Malaria : A Neglected 

 Factor in the History of Greece and Rome." 



To fully grasp the true significance of this 

 historic subject, we must learn something of the 

 nature of malaria, of the life-history of the 

 organism causing the disease, and of how 



