PLATE X. Fig. 19. The mesoglea (M) has granules and some very thin 

 filaments. On the ectodermal (EC) side, it can be clearly seen that the 

 mesoglea is not surrounded by a membrane, but rather extends between the 

 membranes of adjacent ectodermal cells (arrows on the ectodermal side). 

 The membranes of adjacent endodermal (EN) cells can be followed for a 

 considerable distance. The membranes are very dense as they proceed from 

 the mesoglea yielding a terminal bar effect. As the membranes are fol- 

 lowed, accumulations of granules, similar to those seen in the mesoglea, can 

 be found in the extracellular spaces (arrows on the endodermal side). 



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