FILARIASIS. 211 



As regards the life history, Fedschenko showed that the embryos 

 when liberated swam around in water and finally entered the bodies of 

 species of the genus Cyclops. The female tends to come to the surface 

 in the lower extremities, and experiments show that if on the blister-like 

 point of emergence some water be squeezed out from a sponge, the 

 uterus will eject a milky-looking fluid containing myriads of embryos. 

 This would indicate that the worm selects the lower extremity so that 

 the embryos may gain access to the Cyclops when the host is wading 

 through the water. 



Leiper showed that a strength of HC1 equal to that of gastric juice 

 killed the Cyclops, but made the Dracunculus embryos very active. 

 From this he judged that infection must probably take place from 

 drinking water containing infected Cyclops. The disease is known as 

 "Dracontiasis." 



Filaria loa. This is a thread-like worm, about i to 2 inches long. 

 The cuticle is characterized by distinct wart-like structures. The 

 males are smaller than the females and have 3 preanal papillae and 2 

 postanal ones. There are 2 short unequal spicules. The life history 

 is not satisfactorily established. The young are born ovoviviparously, 

 and it has been suggested that the localized cedemas, known as Calabar 

 swelling, may be due to the irritation produced by these eggs. The 

 embryos almost exactly resemble those of F. bancrofti. They have a 

 diurnal periodicity, however, appearing in the blood about 8 A. M., 

 increasing to noon and disappearing about 9 P. M. The intermediate 

 host is unknown. The adult worms have a tendency to w r ander about 

 in the subcutaneous connective tissue, especially about the region of the 

 orbit or even under the conjunctiva. 



Filaria bancrofti. This is the most important of the filarial 

 worms. The embryos have been carried in medical books as Filaria 

 sanguinis hominis. This species is the cause of the common mani- 

 festations of filariasis, such as elephantiasis, varicose groin glands, 

 chyluria, lymph scrotum, etc. 



F. bancrofti is transversely striated, and lives in lymphatics of trunk 

 and extremities. The sexes are usually found together. The females 

 are about 3 inches long and the males less than 2 inches. The tails 

 of both sexes are incurved, but that of the male is more so. The 



