Experiments on the Noctiluca miliaris. 41 1 



in the same way as has just been described with respect to 

 oxygen, the results were much less marlced than might have 

 been anticipated. The Noctihicae confined beneath the ni- 

 trogen continued to live, and to display a vivid phosphores- 

 cence when the bottle was agitated for above the space of a 

 week after the experiment was first instituted. If any differ- 

 ence could be observed between this experiment and the former, 

 it was that the brilliancy of the light was somewhat less in this 

 than in tlie former, being probably about equal to what it 

 would have been if atmospheric air had been employed in 

 place of nitrogen. 



Effects of Nitrous Oxide Gas. — On being submitted in the 

 same manner to the action of this gas, the Noctilucae appeared 

 to be no otherwise affected than under a similar employment 

 of atmospheric air. They were alive and phosphorescent at 

 the end of ten days from the commencement of the experiment. 

 The intensity of the phosphorescence, however, appeared to 

 be neither augmented nor diminished by the action of this 

 gas. 



Effects of Stdphuretted Hydrogen Gas. — On treatnig a por- 

 tion of the luminous water with this gas, the phosphorescence 

 was instantly destroyed, all the Noctilucae being immediately 

 killed ; thus further demonstrating and establishing the well- 

 known power of destructiveness to animal life which charac- 

 terizes this gas. 



Effects of Carbonic Acid Gas. — Of all the gases hitherto 

 noticed, the carbonic acid is the most remarkable in its effects 

 on the luminous sea water. Having filled a bottle with this 

 gas, and introduced it under the water so as to allow a por- 

 tion of the gas to escape and be replaced by the water, in the 

 same manner as in the other instances just related, the lumi- 

 nous property of the water was not only brought out and 

 highly increased, but was rendered permanent for at least a 

 quarter of an hour, during which time the effect might be 

 compared to a bright incandescent glow, of sufficient inten- 

 sity to render the bottle visible from a distant part of the 

 room ; and when approached more nearly, to enable me to 

 discern the hands of a watch by the sole aid of the light thus 

 afforded. At about the expiration of fifteen minutes the light 

 became gradually fainter, and in about twenty or twenty-five 

 minutes had totally ceased ; the darkness, as in the other cases, 

 being evidently connected with the death of the animalculae, 

 which on being brought into the light, could be seen lying at 

 the bottom of the vessel. 



A second bottle of this gas was then procured and employed 

 in the same way, for the purpose of ascertaining the effect of 



