Cii. XV] ORGANS FROM THE ECTO. 



The gill-filaments also carry cilia in the pro x 

 ciliated cell to two non-ciliated cells. The effect 

 becomes less conspicuous after the larvae have reack 

 mm. in length, although even in much later stages the c 

 still found over all parts of the body. Their motion is s. 

 ciently strong to cause the embryo (6 or 7 mm. in length) u 

 move forward, if placed on a glass plate, at the rate of one 

 millimetre in from four to seven seconds. 



j 



