TEICHOCEPHALIDiB OR WHIP- WORMS. 67 



gain the disease. They hatch into small white embryos. 

 Development is direct, no intermediate host being necessary, 

 as has been frequently demonstrated. Their presence can soon 

 be detected by the curious yawning and " gaping " of the host 

 and constant straining forward of the neck. Frequent removal 

 of birds, especially chicks, is the best preventive ; whilst fumi- 

 gation and injection of fluids into the trachea, as mentioned in 

 Appendix I., can be employed as remedies. 



TRICHOCEPHALIDiE OR WhIP-WORMS. 



The Whip-worms are known by having a long, thin, neck-like 

 anterior portion to the body. A small mouth is present at the 

 tip of this long thin region ; it is not provided, as in many 

 worms, with lip-like papilte. They are all small slender worms, 

 with an anus or (in the male) a cloacal opening at the hind end 

 of the body. There is no bursa, as in the Palisade-worms, and 

 one spiculum alone is present. 



The two most noteworthy genera are TrichocejiJialus and 

 Trichina (fig. 25). 



TricJwcephalus is a small worm, with the anterior part of the 

 body much attenuated and whip-like, the posterior part being 

 thick and cylindrical ; this latter contains the generative organs, 

 which are coiled in the male. The eggs are curious citron- 

 shaped, hard-shelled bodies, and undergo their development in 

 water. It is found that the Trichocephalidse require no inter- 

 mediate host, so that they can be taken direct in drinking 

 water or unclean food. 



They do not live free in the gut, but have the whip -like 

 anterior extremity buried in the mucous membrane of the 

 intestine. These worms are found in man, the pig, and the 

 sheep, and cause serious intestinal disturbances. The young 

 worms are hair -like, and resemble very much the trichinae 

 found in pork. 



Another curious form is known as Trichosomum, in which 



