282 



^^ 



^^^ 



B 



Fig. 132 

 Reorganisation of cell-masses from dissociated cells in the sponge Sycon. 

 A, 2-layered stage attained after 5 days, probably by migration of the dermal cells 

 to the exterior and the gastral cells to the interior. B, 34 days, a typical Ascon 

 stage has been reached, with open osculum {osc) and uniradiate and triradiate 

 spicules. See also fig. 27, p. 66. (From Huxley, Phil. Trans. Roy. Soc. B, ecu, 

 1911.) 



