ASCARIDiE AND FILAEIDyl'',. 85 



become so bad in tomato-houses, &o., that the soil has frequently 

 to be removed. The soil may also be burnt, and then will 

 remain free for a long time. 



ASOARID/E AND FiLAEID/K. 



The AscaviiJiii or Round-worms, and the Filarid<ii or Slender 

 Thread- worms, are found in animals and man in various positions, 

 but especially in the intestine. They are often present in very 

 large numbers, yet seldom cause any serious constitutional dis- 

 turbance. They are not only found in man, the horse, pig, dog, 

 and oat, but also in manj' cold-blooded animals. 



The Ascaridce are characterised by the following features : 

 Body fairly stout. Mouth triangular, and furnished with three 

 lips with papillae (fig. 34, f). One is directed towards the 

 dorsal surface, the other two meet together in the ventral line. 

 The male has the end of the body curved, and armed with 

 two spiculae or sickle-shaped hooks (c). 



The Filaridce, on the other hand, may be identified by the 

 following : Body elongated, longer than the Ascarids. Thread- 

 shaped. Six oral papilla often present; sometimes there is 

 a horny oral capsule. There may be two spiculae which are 

 unequal or only one, also four prae-anal pairs of papillEe and 

 an unpaired papilla occasionally. 



The Ascaridse all live in the gut of various animals, especially 

 in the small intestine. The Filarid» take up their abode in the 

 connective tissues. 



The most typical Ascarid worm is the large round worm 

 found in the horse, called Ascaris megalocephala. It is one of 

 the largest species of the genus Ascaris. It is yellowish-white in 

 colour, slightly ridged, and about ten inches long in the $ and 

 six in the male. This worm is common in all Equida^, but 

 only affects seriously young animals. They produce colics and 

 digestive disturbances, and sometimes so obstruct the intestine 

 as to cause death. The ova are nearly globular bodies, and are 



