30 THE MOSQUITO ORIGIN 01' DISEASES 



stage was passed, and so the cycle repeated itself: 

 man— Cyclops— man. 



A further step M'as made when, about 1883, it was 

 shown that the intermediate host of the blood parasite 

 Filaria was the female mosquito, and the suggestion 

 made that man might become infected through the 

 bite of that insect. To Sir Patrick JNIanson we owe 

 most of our knowledge upon this point. By this time 

 observers all over the world were beginning to inquire : 

 How is a disease like malaria carried and spread ? 

 The parasite was known, but how did it enter man ? I 

 need hardly remind the reader of the shelves of books 

 which have been written containing all kinds of fantastic 

 theories. They nearly all centred on the deadly miasm 

 — the malaria or bad pestilential air w^iich, as we have 

 seen, was supposed to arise, carrying the parasites and 

 infecting every one coming in contact with the vapour. 

 There w^ere others, however, as we have seen, who held 

 that possibly tlie ubiquitous gnats or mosquitos miglit 

 have some share in the transmission : for instance, 

 observers like 13eauperthuy, King, Finlay, etc. 



Indeed, with the perfection of our knowledge of 

 the nature of infectious diseases, it was becoming 

 clearer every day that the " domestic " insects which 

 infested and pestered man and animals, sucli as fleas, 

 bugs, ticks, gnats, and flies, could act as disseminators 

 of disease. Already, in the case of red- water in cattle, 

 observers in the States had demonstrated how that 

 disease was carried from animal to animal by the tick, 

 which acted as host and carrier. 



However, returning to the diseases of man, it was 



