TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



attached, was removed from a fresh Echinus, and examined 

 in sea water with particles of carmine in suspension. The 

 particles were always driven back from the madreporite just 

 as they were about to settle. The behaviour of these particles 

 strongly suggested ciliary action on the madreporite. 



Experiment 2. In order to test for any outward flow 

 through the madreporite apart from the action of cilia on its 

 surface, a fresh Echinus was obtained and its madreporite 

 carefully scraped. The madreporite with the stone canal 

 attached was then removed from the animal and examined in 

 sea water with the particles in suspension. All particles were 

 still driven off from the madreporite as though by an outward 

 current. 



Experiment 3. A madreporite with the stone canal 

 attached was placed in a vessel of sea water with particles in 

 suspension, and left for several hours. It was then found that 

 a mass of particles had collected around the cut end of the 

 canal suggesting that there had been an inflow there, and 

 consequently, an outflow through the madreporic plate. 



Experiment 4. Stone canals and ampullae were 

 examined in sea water under a binocular microscope. A 

 continuous circulation was distinctly seen by the movement 

 of the corpuscles in the fluid of the ambulacral system. In the 

 ampullae the direction of this circulation was very indefinite, 

 but in the stone canal there was a very distinct central current 

 towards the madreporite, and peripheral currents towards the 

 oral surface. The peripheral current seemed to be the result 

 of ciliary action on the lining of the canal. 



Experiment 5. Coloured fluid was injected into fresh 

 specimens through the interambulacral areas. The punctures 

 were sealed with plasticine, and the animals kept in fresh 

 sea water for several days (different coloured fluids were used ; 

 e.g., methyl blue, methyl green or fuchsin in sea water ; also 

 carmine in perivisceral fluid). This experiment gave no 



