14 Edmund B. Wilson 



along the septa and body- wall , and downwards in the middle of the 

 stornach-cavity and along the entodermic wall of the Oesophagus. If 

 the entodermic filaments be closely examined , they are not found to 

 produce streng and definite currents , though they are sparsely ciliated. 

 Indeed , this would be nearly impossible because they are constantly 

 changing their form as they are thrown into various convolutions by the 

 contractions of the septa. The straight ectodermic filaments present a 

 very different appearance. Along the ectodermic bands we may 

 observe Constant and power fui upward currents, which 

 may be clearly seen by observing the particles suspended in the gastric 

 fluid. These particles often get into the groove of the filament and may 

 be followed , sometimes for a long distance , as they move rapidly up- 

 wards. In one case I observed a Paraleyonimn in which the gastric 

 fluid was so heavily laden with particles as to appear quite cloudy. In 

 the grooves of the ectodermic bands Constant processious of these parti- 

 cles could be seen coursing rapidly upwards and following the slight 

 undulations of the filaments with the greatest precision. At the upper 

 extremity the currents are discharged upon or into the lower end of the 

 Oesophagus, which is usually held widely open, and then joiu the de- 

 scending currents along the middle of the gastric cavity. 



I was so fortunate as to procure a small transparent specimen of 

 Veretillum in which the circulation could be clearly seen. In the sexual 

 polyps the circulation was precisely as in Alcyonium. The zooids, as 

 in many other Pennaiulida , possess a well-developed pair of dorsal 

 filaments. The currents along the ectodermic bands in the 

 zooids, as in the sexual polyps, are directed strongly 

 upwards. 



These jOservations are enough to afford a stroug presumption that 

 the action oft he ciliaof the ectodermic bands is upwards 

 in a large number of Alcyonaria^ since it is true in the Alcyonida 

 and Pennatulida and in the zooids as well as in the sexual polyps, and 

 the dorsal filaments bave everywhere the same structure and relations. 

 Moreover, it follows that the same is probably true in the young buds, 

 which, as I bave elsewhere pointed out, are identical structurally aud 

 physiologically with the zooids of Pennatulida. 



Whether the direction of the currents is ever reversed I do not 

 know, but I bave examined many different individuals at different tinies 

 and bave always found it Constant. This may possibly happen when 

 the polyps are contracted, but in this condition they cannot be observed. 



The general eutoderm is also ciliated, but to what extent I cannot 



