214 



THE ROUND WORMS. 



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 



FIG. 66. Round worms, i, Encysted embryo of Trichinella spiralis; 2, male 

 and female of T. spiralis; 3, male and female of Trichocephalus trichiurus; 4, egg 

 of T. trichiurus; 5 and 6. head and male and female of Ascaris canis; 7, 8 and 9, 

 head, egg and male and female of Oxyuris vermicularis; 10, n and 12, head, egg 

 and tail of Ascaris lumbricoides; 13 and 14, head and egg of Echinorhynchusgigas; 

 15, 1 6 and 17, parthenogenetic female and rhabditiform and filariform embryos of 

 Strongyloides stercoralis. 



entrance of pathogenic bacteria. They do not seem to produce serious 

 symptoms. 



Trichinella 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 1/20 of an inch long and the female 



