STRONGYLOIDES 75 



They are rarely parasitic in man and only during a 

 portion of their lives the larval stage. The females have 

 long pointed tails. Many of the other families of the 

 Nematoda in their larval stage closely resemble the 

 Anguillulidae. Such larvae with a double dilatation of the 

 oesophagus are known as rhabditiform larvae. 



Two species of Anguillulidae have been described in 

 man. Rhabditis pellio, found in the vagina, and R. niellyi, 

 found in pustules in the skin, but these were immature 

 and possibly were rhabditiform embryos of some species 

 belonging to another family of the Nematoda. 



The better-known Anguillulidae are parasitic on plants. 



Angiostomidcc have a simple unarmed mouth, and in 

 the mature parasitic form a very long oesophagus with- 

 out a double dilatation. The method of development in 

 this group is peculiar and characteristic, as sexual maturity 

 is attained alternately in the parasitic and in free-living 

 forms. These parasitic and non- parasitic sexual forms do 

 not resemble each other. The alternation of generations 

 between sexual maturity as a parasite and sexual maturity 

 as a free-living form, and the marked difference in the 

 characters of the worm when parasitic and when not 

 parasitic are highly characteristic. Several species are 

 known in the lower animals, and one in man, the 

 Strongyloides intcstinalis. 



Strongyloides intestinalis syn. Anguilhila intestinale et 

 stercorale Rhabdonerna intestinale is a very common 

 intestinal parasite in the Tropics ; it is found in Asia. 

 Africa, and America, in the South Pacific Islands and the 

 West Indies. 



The adult parasitic form is T 2 mm. in length and 

 0*034 mm. in breadth. It is nearly cylindrical and is 

 found in the mucosa and on the surface of the mucosa in 

 the small intestine, and is most readily found on examin- 

 ing scrapings of the mucosa. When there are pouches in 

 the intestinal wall these parasites are usually to be found 

 in large numbers in them. The mouth has four lips, 

 the oesophagus is nearly a quarter the length of the body, 



