248 Remarks on Marine 



ART. Ilf. Remarks on Marine Luminous Animals. By 

 J. MAC CULLOCH, M.D., F.R.S , % c . 



' [Communicated by the Author.] 



IN my work on the Western Islands of Scotland, I had occa- 

 sion to take notice of the causes which produce that -beautiful 

 appearance of light in sea water, so well known to seamen, and 

 to all indeed who have been in the least conversant with the 

 sea during the darkness of night. I there attempted to prove, 

 that if, in every case it did not arise from the action and pro- 

 perties of living animals, but was sometimes owing to the lumin- 

 ous matter of fish dispersed through the water, yet that all the 

 most conspicuous appearances of this nature were produced by 

 these, and that the brilliant sparks of light, in particular, were 

 always to be traced to some of the vermes or insects, which 

 abound in the waters of the sea. 



I have also given a list of such of these animals as had, by 

 various naturalists, been found to possess this remarkable pro- 

 perty; and had occasion to lament how circumscribed it was ; 

 partly owing to the deficiency of observers in this department of 

 Natural History, and partly owing to unfounded theories re- 

 specting the nature and causes of the light of the ocean ; in 

 consequence of which, those who possessed the opportunities 

 of extending this examination, had neglected it. I have also 

 observed that many animals either very minute, or absolutely 

 microscopic, and invisible without the use of a lens, existed 

 in the sea; and that the neglect of these more obscure 

 creatures, had probably been one reason why the property of 

 emitting light was referred to the water itself, when it was, in 

 fact, owing to these unsuspected animals existing in it. 



The further investigation of this department of Natural His- 

 tory, was, in that essay, recommended to those who might have 

 opportunities of pursuing it, as the subject had not at that time 

 practically engaged much of my time, being occupied by geolo- 

 gical pursuits requiring undivided attention, and every leisure 

 moment of the night being employed in registering the obser- 

 vations of the day. But as it is not often that observers feel 



