12 DISCOLOURED SEA. [CHAP. i. 



quite hollow case. The formation of the granular sphere was hastened 

 by any accidental injury. I may add, that frequently a pair of these 

 bodies were attached to each other, as represented above, cone beside 

 cone, at that end where the septum occurs. 



I will here add a few other observations connected with the dis- 

 colouration of the sea from organic causes. On the coast of Chile, 

 a few leagues north of Concepcion, the Beagle one day passed through 

 great bands of muddy water, exactly like that of a swollen river ; and 

 again, a degree south of Valparaiso, when fifty miles from the land, 

 the same appearance was still more extensive. Some of the water 

 placed in a glass was of a pale reddist tint; and, examined under 

 a microscope, was seen to swarm with minute animalcula darting about, 

 and (often exploding. Their shape is oval, and contracted in the middle 

 by a ring of vibrating curved ciliae. It was, however, very difficult 

 to examine them with care, for almost the instant motion ceased, even 

 while crossing the field of vision, their bodies burst. Sometimes both 

 ends burst at once, sometimes only one, and a quantity of coarse, 

 brownish, granular matter was ejected. The animal an instant before 

 bursting expanded to half again its natural size ; and the explosion 

 took place about fifteen seconds after the rapid progressive motion had 

 ceased: in a few cases it was preceded for a short interval by a 

 rotatory movement on the longer axis. About two minutes after any 

 number were isolated in a drop of water, they thus perished. The 

 animals move with the narrow apex forwards, by the aid of their 

 vibratory ciliae, and generally by rapid starts. They are exceedingly 

 minute, and quite invisible to the naked eye, only covering a space 

 equal to the square of the thousandth of an inch. Their numbers were 

 infinite ; for the smallest drop of water which I could remove contained 

 very many. In one day we passed through two spaces of water thus 

 stained, one of which alone must have extended over several square 

 miles. What incalculable numbers of these microscopical animals ! 

 The colour of the water, as seen at some distance, was like that 

 of a river which has flowed through a red clay district; but under 

 the shade of the vessel's side it was quite as dark as chocolate. The 

 line where the red and blue water joined was distinctly defined. The 

 weather for some days previously had been calm, and the ocean 

 abounded, to an unusual degree, with living creatures.* 



In the sea around Tierra del Fuego, and at no great distance from 

 the land, I have seen narrow lines of water of a bright red colour, 

 from the number of Crustacea, which somewhat resemble in form 

 large prawns. The sealers call them whale-food. Whether whales 



* M. Lesson (Voyage de la Coquille, torn, i., p. 255) mentions red water 

 off Lima, apparently produced by the same cause. Peron, the distinguished 

 naturalist, in the " Voyage aux Terres Australes," gives no less than twelve 

 references to voyagers who have alluded to the discoloured waters of the sea 

 (vol. ii., p. 239). To the references given by Peron may be added, Hum- 

 bold t's " Pers. Narr.," vol. vi., p. 804 ; Flinders' " Voyage," vol. i., p. 92; Labil- 

 ladiere, vol. L, p. 287 ; Ullioa's " Voyage " ; "Voyage of the Astrolabe and ot 

 the Coquille " : Captain King's " Survey of Australia," etc. 



