488 DISEASES OF THE CIROULATOBY SYSTEM. 



according to Manson it passes through six stages of development. 

 The fcDiale mosquito lays its eggs and goes to die in the water ; the 

 worms then travel through its tegmentary skeleton and swim freely 

 in the water. Man may thus become infected in two ways r 

 through the sting of a mosquito containing threadworms when it 

 comes to suck blood, or through the ingestion of water holding the 

 embryo of these parasites in suspension. According to Sonsino^ 

 the threadworm of human blood is also frequent in Egypt, where 

 it is developed in the body of the common gnat ( Culex pipiens). 

 The infection of the dog must occur in the same way. 



