MdNOCYSTIS' 



15s 



about for a short time in the worm's -sperm-sacs, the free 

 and mature Monocystis conjugates and encysts. Two 

 individuals come together, and are attached to one another 

 by their broader ends. In this condition each individual 



A 



Fig- 32- 

 A^ a free specimen of Monocystis a^Hs', nu, nucleus. 5", sperm- 

 motber cells adhering to the parasite, i)', a free monocystis 

 covered with ripe spermatozoa, and thus appearing as if covered 

 with a coat of long cilia. C, a ripe cyst of Monocystis agilis 

 containingnumerouspseudonavicellae/.rff. {A and .5, original ; 

 C, after Lankester.) 



is termed a zygote (Greek C^y^, a yoke, because the two 

 are yoked or joined together). The zygotes contract into 

 spherical form, and each contributes to the formation of a 

 common transparent protective case or cyst-wall, composed 

 of chitin-like substance. At first the contours of the cyst 



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