154 



ZOOLOGY 



complicated series of stages to go through before it be- 

 comes adult. Thus the flukes in the liver of the sheep 

 produce eggs which develop into embryos. These em- 

 bryos get out of the liver into the food canal, and thence 



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ec.10. 



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 Jan.25. FA.5. Fe~b,17 



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Jan. 2 5.' 



FIG. 143. Showing results of cutting Planarians into two pieces ; the pieces 

 develop into entire animals. After Morgan. 



to the exterior. If they are deposited near a pool of 

 water, they may develop further, otherwise they must 

 die. In the water a ciliated larva l hatches from each 

 egg, swims about for a time until it finds a fresh-water 

 snail, bores into it, and encysts itself there. In this 



1 Fig. 146, A. 



