Ib 



54 HELMINTHOLOGY 



of diaphragm of the rat or pig infested with Trichinella spiralis. 

 Count the number of cysts for a given area, e. g. i sq. cm. 



b. Examine the specimen with the naked eye. Can you see 

 the cysts? 



c. Is there any general position that the trichina has taken 

 within the cyst? 



d. Find trichinae that show advanced stages of calcification. 



e. Examine the adjacent muscle fibres to determine effect on 

 the same. 



Draw a characteristic specimen of trichina, showing it in its 

 relation to the muscle. 



EXERCISE 30a 



THE FILARIJE 



PHYLUM NEMATHELMINTHES, CLASS NEMATODA, FAMILY 

 FILARIIDJ2 



A. Characteristics of Filariida. "Body long, filiform; mouth 

 surrounded with papillee, or provided with two lips ; oesophagus 

 slender, without posterior bulb. Males with single spicule or 

 two unequal spicules. Females with two ovaries, vulva usually 

 in front of middle of body. Usually oviparous. Development 

 in many cases requires an intermediate host." (Ransom.) The 

 Filariae are extremely slender hair-like worms inhabiting the 

 blood and lymphatic fluids. They range in length from micro- 

 scopic species, such as Microfilaria bancrofli, to the extremely 

 long guinea worm, Filaria medinensis, which probably averages 

 90 cm. in length. (Manson.) 



B. Microfilaria bancrofli (Filaria nocturna). Examine a 

 prepared slide of human blood taken from a patient suffering 

 from elephantiasis, a disease caused by the presence of filariaa 

 in the lymphatic vessels. 



