NEMATHELMIA. 



53 



7. Sense Organs are only represented by tactile papilla, in which 

 nerves terminate. There are two of these on the dorsal lip, one 

 on each ventral lip, and others near the anus (or cloacal aper- 

 ture). 



LIFE-HISTORY. 



In both Ascaris lumbricoides and A. megalocephala the eggs pass 

 out of the intestine of the host, and embryos develop within 

 them which may be liberated on damp soil, &c. Infection results 

 from the swallowing of these eggs or embryos. A. lumbricoides, 

 however, may perhaps pass into an intermediate host, Julus 

 guttulatus, a small millipede. 



Other Nemathelmia. 



Oxyuris Vermicularis (the thread-worm) is probably the commonest 

 parasite of the kind found in the human subject. It occurs throughout the 



Fig. 16. OXYURIS (from von 

 Jaksch). a, Head; b, female; 

 ' c, male ; d, eggs. 



Fig. 17. TRICHINA (from von 

 Jaksch). a, Male ; b, female ; 

 c, encysted young. 



