92 HISTORY OF BRITISH ZOOPHYTES. 



luminous as those of the TJydroida. I had not the oppor- 

 tunity, indeed, of trying the experiment on it in the sea, 

 but wlien quite ahve in a vase of sea-water, I found that it 

 emitted, wlien smartly touched, a flash of phosphorescent 

 light. When I brought hydroid zoophytes from the sea 

 in a close vasculum, the sea-water adhering to the seaweeds 

 kept them as much alive during the transit, occup}ing less 

 than half an hour, as if they had remained on the rocks on 

 which the seaweeds grew, and where many of them, during 

 every ebb-tide, are quite deserted by the sea. Taking them 

 into a darkened room half an hour after they were removed 

 from the rocks, I found the phosphorescent light, when they 

 were shaken, quite brilliant. The experience of Mr. William 

 Thompson, of Belfast, an accurate observer, seems to have 

 been the same. He remarks, '^ I do not think it probable 

 that the luminosity of zoophytes is caused by partial decay 

 and decomposition, as I have, especially in the month of 

 January, 1834, and frequently since, observed many species 

 to put forth their lights vigorously a very few hours — cer- 

 tainly within three — after I had dredged them from the 

 bottom of the sea. They were not sooner looked at, because 

 it was not dark till about that time after their capture. 

 Tom from their attachments these certainly were, but they 



