74 



SPONGES 



some parenchymulae paves the way for an important variation in the 

 mode of formation of the inner mass. We have seen that in CI. blanca 



ft; 

 o 



O 



S5 

 CO 



immigration of cells takes place at any point. When there are no pos- 

 terior granular cells, however, the iinmij^rntion may be entirely restricted 

 to the posterior pole, so that the hinderinost flagellated cells become con- 



