•"94 EAMBLES OF A NATURALIST. [Oh. XXin. 



forms of luminosity are exhibited or not, sparks of light in 

 greater or less abundance are scarcely ever absent. The 

 sea, more particularly when agitated, sparkles with brilliant 

 poiuts of light, varying in size from that of a pia's head to 

 that of a pea, and of greater or lesser permanency — some 

 being almost instantly extinguished, while others retained 

 their light for an appreciable length of time. I do not think 

 I ever looked at the sea on a dark night without seeing 

 some few sparks, even though I might have entered a 

 remark that the sea was "not luminous to-night." But 

 usually these sparks are abundant, and on occasions they 

 present a wonderfully brilliant appearance. On one occa- 

 sion, when this phenomenon was unusually striking, on the 

 coast of China in lat. 26° N., on drawing up bottles fuU of 

 water, and pouring it out in the dark, the water sparkled 

 brightly as the luniinous points ran over ; but a close 

 inspection revealed nothing in the water but a few minute 

 Entomostraca. On another occasion, when some water 

 which had been left in a basin exhibited luminosity at night, 

 I got a very brilliant spark upon my finger, and taking it to 

 the light, it proved to be a minute crustacean of the same 

 division. I do not mean to say, however, that these sparks, 

 when thus appearing as distinct and segregated scintilla- 

 tions, are always due to Entomostraca. There are many 

 other minute creatures which exhibit luminosity ; but I wish 

 to draw a distinction between this form and that next to be 

 described, which appears to be mainly due to one organism, 

 which, owing to its occasional great abundance, produces 

 phenomena conveniently distinguishable from this common 

 and almost universal one. 



' The second form of luminosity then to be noticed occurs 

 comparatively rarely. It consists of a soft, usually greenish 



