TROPICAL MEDICINE AND HYGIENE 



been extracted and there are Calabar swellings, but no 

 Mf. diurna have been found in the blood. 



The intermediate host has been proved by Leiper to 

 be a Chrysops. Both C. dimidiata and C. silacea have 

 been proved to be carriers. It is interesting to note 

 that many years ago a specimen of C. dimidiata was 

 deposited by Manson in the British Museum with the 

 note that it was called by the natives the " Mangrove 



FlG. 51. Chrysops dimidiata. 



Fly," and believed by them to be the cause of Calabar 

 swellings. The fact that the embryos are not found in 

 the blood at night renders it improbable that any of 

 the domestic species of mosquitoes are the carriers, 

 though many jungle mosquitoes are preferentially day- 

 feeders and experiments have shown that mosquitoes are 

 not carriers. The embryos, after leaving the stomach, 

 migrate to the salivary glands and there undergo the full 

 development up to the stage where they are sufficiently 

 mature to be introduced into the warm-blooded host. 



