PLATE XIV. Fig. 26. Section through the hypostome showing relations of 

 ectoderm, endoderm and mesoglea (M). The epithelio-muscular cell (EP) 

 contains vacuoles, organelles and inclusions as described previously and 

 muscle filaments in its base. The digestive cells of the endoderm (EN) con- 

 tain vacuoles, organelles and inclusion bodies and have muscle filaments in 

 their base. S is the surface of the animal. 



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