152 ANTHOZOA ASTEROIDA. 



Others had the membrane, or sac, surromicHng the stem, flac- 

 cid and undistended by water, and I was informed were in a 

 less hvely condition. They phosphoresced, however, very 

 readily when struck, and were used indiscriminately with the 

 more vigorous ones in the experiments I made. 



" These experiments were of a very simple kind. They 

 consisted in placing- the Pennatula in an insulating or non-con- 

 ducting medium, and, whilst it was made to phosphoresce by 

 touching it with a glass rod, placing it in communication with 

 a delicate electroscope or galvanometer. The most convenient 

 insulating medium for this purpose was the air, to which the 

 Pennatula was transferred from the sea-water, and dried by 

 blotting-paper or a soft towel. It was neither possible, nor 

 was it attempted by this method, to remove the whole of the 

 water from the surface of the animal ; but the power of that 

 surface to conduct electricity was, at all events, rendered ex- 

 ceedingly slight. 



" Thereafter plates of platina, connected with each of the 

 wires of a galvanometer, were placed on opposite sides of the 

 animal, so as to receive and carry off any electrical currents 

 generated by it. 



" In no case was the needle of the galvanometer affected, 

 although the position of the plates was varied greatly. One, 

 for example, was placed on the one flat surface, and the other 

 on the other, whilst the animal was made to phosphoresce. 

 Again, whilst one of the plates was buried among the polypes 

 at the plumed end, the other was made to irritate the animal 

 near its quill-like extremity, so that the phosphorescing surface 

 was between the plates ; but the needle did not move. In 

 short, no action on the galvanometer could be obtained by any 

 method of treating the Pennatula, 



" Similar experiments were made by immersing the Penna- 

 tula in turpentine, an excellent non-conductor, but with equally 

 negative results. 



" A number of trials were likewise made with gold-leaf 

 electroscopes of different construction, one of which I had 

 made of peculiar delicacy, solely for the purpose of trying the 

 experiments I am recording. In using them the animal was 

 simply dried, held by the stem, and, whilst it was phosphoresc- 

 ing powerfully, approached to the electroscope. The latter, 



