84 



ORGANISMS OF TISSUES 



ing is made up of the epithelio-muscle cells, while sensory cells 

 are 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 fusca as seen in optical section through the enteric cavity; 

 two testes are 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 



