io8 



ZOOLOGY 



Fig. 73. — Five stages in the life-histovy ot Fasciola liepaiica, all highly magnified. 



A. The free-swimming embryo. 10. 



B. The sporocyst containing young rediae. 



C. The young redia, the digestive tract 11. 



shaded. 12. 



D. An adult redia, a daughter redia, two 1 3. 



cercariae, and germs. 14. 



E. The free cercaria. The figures have Ifi. 



the same significance throughout. 16. 



1. Nearly ripe cercariae. 17. 



2. Cystogenous cells. 18. 



3. Daughter rediae. 



4. Limbs of the digestive tract. 19. 

 b. Head papilla. 20. 



6. Eye-spots. 21. 



7. Same degenerating. 22. 



8. Germinal cells. 23. 



9. Cells of the anterior row. 



Embryo in optical section, gastrnla 



stage. 

 Pharynx of redia. 

 Digestive .sac. 

 Oesophagus. 

 Lips of redia. 

 Collar. 



Processes serving as rudimentary feet. 

 Embryos. 

 Trabeculae crossing body-cavity of 



redia. 

 Birth opening. 

 Morulae. 

 Oral sucker. 

 Ventral sucker. 



Pharynx. All from Marshall and 

 Hurst, after Thomas. 



