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TEXTBOOK OF ZOOLOGY 



respiration by collecting the excess water and carbon dioxide. The 

 oxygen is received into the body with water which diffuses through 

 the body wall. A large ganglion, located in a dorsoanterior position 

 and several nerves extending to sense organs and muscles con- 



- Tactile organ 



.Brain 



—Eye 



Tooth 

 "Mastax 

 Salivary 



gland 



Stomach- 

 intestine 



- Vitellarium 



-Egg 



Blasendarm" 



_ Contractile 



bladder 

 -Rectum 



— Anus 

 - Foot-gland, 



-r\ — Pharynx 



Salivary 

 gland 



Salivary 

 gland 



Flame cell 



Excretory 

 canal 



Fig. 96. — A common fresh-water rotifer, Philodina roseola, showing internal 

 structure, a, dorsal view; b, ventral view. (From Hegner, College Zoology, 

 published by The Macmillan Company, after Hickernell.) 



stitute the nervous system. The body wall is composed of an outer 

 cuticle over a thin layer of ectoderm. Under this layer is the meso- 

 dermal tissue which includes mesenchymatous cells and muscle fibers. 



