2GS 



CGELHELMIXTHES 



Emmersleben, Saxony, in 1SS4, where 57 died in four weeks from infection 

 from one pig. 



Family 5. Fil^riid.e. Extremely elongate, hair-like worms. Dracioiculus 

 medincnsis, the guinea worm (_the female about a yard long, and about as large 

 as stout packing twine), produces abscesses beneath the skin in Avhich the 

 worm is coiled up. The embryos break through the wall of the mother and 

 must enter the water and penetrate a small crustacean, Cyclops. It is appar- 

 ently introduced into the human system by swallowing the Crustacea with drink- 

 ing water. The worm occurs in tropical America. 



FUaria sanguinis Jio»iiiiis, 3 to 6 inches long, li\es in the lymphatic glands of 

 man, the young escaping into the blood, often in immense numbers. They 

 often pass through the kidneys, where they produce serious disturbance. There 

 is possibly a connection between them and elephantiasis. The intermediate 

 host is apparently the mosquito. As yet they are known only in the tropics. 

 Other species occur in man and other animals. 



Family 6. !Mermithid.e. Elongate nematodes in the body cayity of insects; 

 they pass into damp earth, where they become sexually mature. They share 

 with the Gordiacea the name 'hairworms.' Mcnnis.'^ 



Order II. Gordiacea. 



The hairworms resemble the nematodes in general appearance, but differ 

 greatly in structure. The body cayity has both splanchnic and somatic ejiithe- 

 lium; the intestine is supiported by mesenteries (fig. 249); there is an tvsophageal 



Fig. 24Q. — Trans\'ersc section ot wiuhl; iiord/KS Uiflcr von I.instowV (7, h\'po- 

 dcrmis; h. muscular layer; c. cuticle; d. parenchyma; f, /', muscles and mesenteries; ^c, 

 alimentary canal; /;, neryous system. 



nerye ring and unpaired yentral ncrye cord, and the female genitalia open info 

 the cloaca. The adults liye in water, where they lay their eggs; the larya' liye 

 in insects, there being in some cases an alternation of hosts. They are popularly 

 belieyed to be horse hairs changed into worms. Gordiiis* Cho'rdojcs* Near 

 the Gordiacea must be mentioneil the marine Xccloiiciiia,'^ young stages apjiar- 

 ently passed in the mosquito. 



Order III. Acanthocephala. 



The adult spine-headed worms li\-e in the alimentary canal of yerlebrales. 

 They resemble the Ascarid;e (p. 266), but are easily distinguished by the jiro- 



