82 



PORIFERA 



CHAP. V 



Saviile Kent, and since rediscovered both in England and 

 abroad.^ This is a colony of unicellular individuals emljedded 

 in a common jelly. The individuals at the surface are 

 choanoflao-ellate, while in the interior the cells are rounded 



Fig. 75. — Proferospongia haeckeli. a, Amoeboid cell : h. a cell dividing : r, cell 

 with small collar ; z, jelly. x 800. (After S. Kent. ) 



or amoeboid, and some of them undergo multiple fission to form 

 reproductive cells. This is just such a creature as we might 

 imagine that ancestral stage to have been of which the free- 

 swimming sponge larva is a reminiscence : for we have seen 

 that the flagellated cells of the larva are potential choanocytes. 



^ France, Organismus der Craspedomonadcn, Budapest, 1S97, p. 217. 



