THE WHIP WORM 



321 



B. Absence of sheath. None of these exhibit a periodicity, being continuously pre- 

 sent. 



1. Blunt tail F. perstans. 200 X 4.5;*. 



2. Sharply pointed tail: 



(a) F. demarquayi. 210 X SM- 



(b) F. ozzardi. 215 X SM- 



(c) O. volvulus. 250 3oo/i X 7-5M- 



NOTE. A filarial embryo, F. powelli, reported once. It has a sheath, nocturnal 

 -periodicity, and is about 130 X SM- 



TRICHOTRACHELID^E 



These have a long thin neck and a thicker terminal portion. The 

 oesophagus is of the single row of cells type. The anus is terminal; 

 there is only one ovary. 



Trichuris trichiura (Trichocephalus dispar). This is usually called 

 the whip-worm the thickened body representing the handle and the 

 narrow neck the lash. It is one of the most common parasites in both 

 temperate and tropical climates. 



The egg is very characteristic in having an oval shape with knobs at either extrem- 

 ity. It resembles a platter with handles. The male is almost 2 inches long, and has 

 the terminal portion curled up in a spiral. It has a single terminal spicule. 



The female is a little longer than the male, and has the terminal part in the shape 

 of a comma instead of being coiled. The neck only contains the oesophagus which 

 is contained in a groove in large cells which form a single row like a string of pearls. 

 These cells play a digestion role. The vulva opens at the upper end of the thickened 

 terminal end which contains an intestine lying between the ovary and uterus. The 

 great powers of resistance of the ova may account for their general distribution; 

 they may live for months under conditions of freezing and so forth. There is no 

 intermediate host. The worm arrives at sexual maturity in about one month after 

 ingestion. The whip-worm prefers the caecum, but also lives in the lower end of the 

 ileum and the appendix. 



The neck burrows into the mucosa, and much importance has been attributed by 

 the French to the possibility of this paving a way for the entrance of pathogenic 

 bacteria. They do not seem to produce serious symptoms. 



Trichinella spiralis (Trichina spiralis). The cause of trichinosis is 

 usually termed Trichina spiralis in medical works. 



The adults live in the duodenum and jejunum; the males are about KG i ncn 

 (1.5 mm.) long with two tongue-like caudal appendages and without a spicule. 

 These two lateral projections enable the male to hold the female in copulation 

 the cloaca being evaginated to act as a penis. 



The females are about M inch (3 to 4 mm.) long. The female gives off 

 embryos from the vulva which is near the mouth end (viviparous). 



