82 



ORGANISMS OF TISSUES 



rare and limited to the regions about the mouth and the pedal 

 disc. The nettle or stinging cells are superficially placed on the 

 epithelial cells and partly embedded in them. The nerve and 

 interstitial cells lie between the bases of the epithelial cells and 

 upon the supporting lamella. 



FIG. 34. Hydra jusca as seen in optical section through the enteric cavity; 

 a testis is shown just below the tentacles and an ovary farther down; on the 

 opposite side a well-developed bud. (Modified after Marshall and Hurst.) 



i. The Epithelio-muscle Cells. There is no muscular system in 

 Hydra the covering, or epithelial cells possessing contractile 

 processes which take the part of muscles in higher animals. 

 These cells are much elongated in the gonad region and on the 

 pedal disc where the cells are loaded with granules of secretion 



