172 ATLANTIC OCEAN chap. 



time. The central and intertropical parts of the Atlantic 

 swarm with Pteropoda, Crustacea, and Radiata, and with their 

 devourers the flying-fish, and again with their devourers the 

 bonitos and albicores ; I presume that the numerous lower 

 pelagic animals feed on the Infusoria, which are now known, 

 from the researches of Ehrenberg, to abound in the open ocean : 

 but on what, in the clear blue water, do these Infusoria 

 subsist ? 



While sailing a little south of the Plata on one very dark 

 night, the sea presented a wonderful and most beautiful spec- 

 tacle. There was a fresh breeze, and every part of the surface, 

 which during the day is seen as foam, now glowed with a pale 

 light. The vessel drove before her bows two billows of liquid 

 phosphorus, and in her wake she was followed by a milky 

 train. As far as the eye reached, the crest of every wave was 

 bright, and the sky above the horizon, from the reflected glare 

 of these livid flames, was not so utterly obscure as over the 

 vault of the heavens. 



As we proceed farther southward the sea is seldom phos- 

 phorescent ; and off Cape Horn I do not recollect more than 

 once having seen it so, and then it was far from being brilliant. 

 This circumstance probably has a close connection with the 

 scarcity of organic beings in that part of the ocean. After the 

 elaborate paper -^ by Ehrenberg, on the phosphorescence of the 

 sea, it is almost superfluous on my part to make any observa- 

 tions on the subject. I may however add, that the same torn 

 and irregular particles of gelatinous matter, described by 

 Ehrenberg, seem in the southern as well as in the northern 

 hemisphere to be the common cause of this phenomenon. 

 The particles were so minute as easily to pass through fine 

 gauze ; yet many were distinctly visible by the naked eye. 

 The water when placed in a tumbler and agitated gave out 

 sparks, but a small portion in a watch-glass scarcely ever was 

 luminous. Ehrenberg states that these particles all retain a 

 certain degree. of irritability. My observations, some of which 

 were made directly after taking up the water, gave a different 

 result. I may also mention, that having used the net during 

 one night, I allowed it to become partially dry, and having 

 occasion twelve hours afterwards to employ it again, I found 



^ An abstract is given in No. IV. of the Magazine of Zoology and Botany. 



