396 



ANIMAL BIOLOGY 



The adult Liver Fluke is a worm about an inch long which 

 lives in the bile ducts of the liver of Sheep, Cattle, Pigs, etc., and 

 occasionally in Man. It is hermaphroditic, each individual pos- 

 sessing both male and female reproductive organs, and in its iso- 

 lated position is almost continually producing fertilized eggs. In 

 fact, one Fluke may liberate over five hundred thousand eggs 



Sarcocystis hominit — y£ — — * 



[Paragonimus loestermani 

 \Ascaris lumbricoides (larva) 



Trypanosoma cruzi 



Trypanosoma gambiense — 

 Plasmodium falciparum — 

 Leishmania donovani 



Giardia lamblia \ 

 Isospora hominis ) 



Balantidium coli 

 Endarrweba histolytica 

 Endamoeba coli 



Trichomonas hominis 



Trichomonas vaginalis — f — — — 



( Echinococcus granulosus 

 \ Cbnorchis sinensis 



{ Asearis lumbricoides 

 \ Ancylostoma duodenale 

 j Taenia solium 

 i Diphyllobothrium latum 



Schistosoma mansoni 

 Enterobius vermicularis 



Trichuris trichiura 



_ Wuchereria bancrofti 

 ( lymph nodes ) 



\- Phthirius pubis 



Fig. 250. — The chief points of localization of some 

 organs of the human body. At the left are Protozoa; 

 (After Hegner.) 



— 4- Schistosoma haematobium 



of the parasites in the 

 at the right, Worms. 



which pass down the bile ducts of the host (sheep) into the intes- 

 tine and finally leave the body with the feces. An egg that happens 

 to reach moisture develops into a ciliated larva, or miracidium, 

 which escapes from the egg-shell and swims about. For further 

 development to occur the larva must encounter within a few hours 

 a certain species of fresh-water Snail, otherwise death results. 

 But once it has bored into a snail's body, the parasite receives 



