NOSTOCHINE^. 275 



served by others. I reproached myself for not having ques- 

 tioned the Arabian pilot whom we had on board, and who 

 for twenty years traversed that sea. This idea unhappily 

 presented itself too late. 



" If it should be in your opinion worth the pains, I would 

 demand new observations of the surgeon or officers of the 

 Atalanta, for it would be easy for me to write to them by 

 way of Alexandria. 



" Believe me, my dear Geoffrey, &c. 



" EVENOB DUPONT." 



Numerous other navigators and naturalists have noticed the 

 colouration of different portions of the ocean, but these for 

 the most part have not determined the exact nature of the 

 cause, most of them attributing the phenomenon to minute 

 animals. Crustacea and Molluscce. Two English naturalists, 

 in describing it, have distinctly stated the cause to be an 

 Alga, the species of which, however, they did not determine. 

 The first of these, Mr. Darwin, observed the phenomenon 

 in the Atlantic ocean near Brazil, and not far from the Isles 

 of Abrolhos. The other, Dr. Hinds, of H. M. ship Sulphur, 

 encountered the same Alga at the same spot in which it was 

 originally discovered by Mr. Darwin, and again observed it 

 in the month of April 1837, while at anchor at Liberty, near 

 San Salvador, upon the western coast of America, latitude 

 14 north. Mr. Hinds on both occasions remarked that the 

 plant emitted a strong and penetrating odour, and many 

 persons on board experiencing an irritation of the eyes, fol- 

 lowed by an abundant secretion of tears, attributed the af- 

 fection to the presence around the ship of the Alga. Mr. Hinds 

 took the precaution to preserve specimens of his plant, some 

 of which were entrusted to Mr. Berkeley for publication, 

 who forwarded them to Dr. Montagne, who ascertained that, 

 though belonging to the genus Trichodesmium, the plant was 

 specifically distinct therefrom, and named it T. Hindsii. 



I have been led, in having introduced the above account of 

 the colouration of the waters of the sea, to depart from the 

 strict limits of this work. The phenomenon is, however, so 



T 2 



