35 



of the mosquito they enter the Malpighian tubes, undergo a meta- 

 morphosis, develop rudimentary sexual organs, and finally, about the 

 twelfth day, destroy the tubes of the mosquito and come to lie in 

 the proboscis. When such an infected mosquito bites a dog the 

 larvae pass to the heart of the dog and there develop into the adult 

 stage. 



Related species — Filaria bancrofti a very common parasite of 

 man in the tropics, being one of the causes of elephantiasis. It was 

 in this species that the agency of the mosquito as an intermediate 

 host was first worked out. F. medinensis, or guinea- worms undergo 

 one stage in crustaceans Cyclops. Another species of Filaria is very 

 common in the blood of crows, almost 50 per cent of those about 

 Ithaca being infested. Its life cycle has not been satisfactorily 

 worked out. 



Dispharagus hamulosus — A representative of the family Filariidae 

 which infests the gizzard of chickens, being imbedded in the muscles. 

 It has been reported a few times from widely remote regions (Brazil, 

 Italy), but seems to be not uncommon in New York State. Life 

 history not known but it has been thought that the sow-bugs or pill 

 h\igs^{Oniscus) serve as intermediate hosts. The ravages of this 

 parasite seem to be serious and the" writer would be glad to receive 

 specimens or any data to aid in a study of life history. 



Family GNATHOSTOMIDAE 



Gnathostomum hispidum — Found in the stomach of hogs. Not 

 discussed in this course. 



Family ANGUILLULIDAE 



Anguillula aceti — The vinegar eel. This nematode which nor- 

 mally lives free and is very commonly found in vinegar, has been 

 reported several times as occurring in the human bladder. See Stiles 

 and Frankland, '02. 



Other species of this family, normally living on vegetables, have 

 been occasionally 'reported as parasites of man. 



Family STRONGYLOIDES 



Strongyloides stercoralis — The Cochin China diarrhoea worm. 

 Occurs primarily in the tropics but cases are occasionally imported. 



