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Show 16 ATLANTIC OCEAN. Mar. 1832. d . th. n the extreme co m.e a1 p oints . In some, not exten Wl 1 · h ranular matter sup-small but perfect spheres of bro~l; o~served the curious plied the place of the septa ; dan d The pulpy matter of b h' h they were pro uce . process Y w lC d itself into lines, some the internal coating suddenly ~ro~pe a common centre ; of which assumed a. form ~admtl~~ ~::ra id movement, to it then continued, With an uregu of a s;cond the whole contrac~ itse~, so tha~f:~ t~:t~o~;~ere, which o~cupied t?e was umted mto ape d f the now qmte . . f th eptum at one en o pos1t10n o e s if an elastic mem- Th appearance was as hollow case.. e hin Indian-rubber ball, had been brane, for ~nhsta~ce a dt then burst in which case tha distended w1t au, an ' wards a es would instantly shrink up and contract to ed? t The formation of the granular sphere was hast~ned p1o man .y ace1. denta l m. J. ury. I may add ' that frequent y a PJ~ir of these bodies were attached to each other, as brep~desented in the accompanym. g rud e dra wl' ng' cone es1 c cone at that end where the septum occur s • Whenh flo. at-1 ing ~ninjured in the sea, the formation of the sp ~nc: gemmules perhaps only takes place, when stwovo·f thet)p tahnu: (or rather am. mals, accor di ng t o Bory t. mcen h 1 become attached, and married to each oth~r. Nevert. e ~s~~ I certainly witnessed this curious process m several mdlvl duals, when separate, and where there was no apparent cause of disturbance. In any case it does not seem probable, from the fixed structure of the septum, that the whole of the granular matter is transferred from one to the other body, as with tbe true Conjugatre. . . h I will here add a few other observatwns connected Wlt the discoloration of the sea from organic ca~ses. On ~he coast of Chile, a few leagues north of Concepcwn, the ~eaole one day passed through great bands of muddy water' and Mar.l832. PELAGIC ANIMA.LCULA. 17 again, a degree south of Valparaiso, the same appearance was still more extensive. Although we were nearly fifty miles from the coast, I at first attributed this circumstance to real streams of muddy water brought down by the river Maypo. Mr. Sulivan, however, having drawn up some in a glass, thought he distinguished, by the aid of a lens, moving points. 'l'he water was slightly stained as if by red dust; and after leaving it for some time quiet, a cloud collected at the bottom. With a lens, of one-fourth of an inch focal distance, small hyaline points could be seen darting about with great rapidity, and frequently exploding. Examined with a much higher power, their shape was found to be oval, and contracted by a ring round the middle, from which line curved little setre proceeded on all sides ; and these were the organs of motion. One end of the body was narrower and more pointed than the other. According to the arrangement of Bory St. Vincent, they are animalcula, belonging to the family of 'l'richodes : 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, which cohered very slightly. 'l'he ring with the setre sometimes retained its irritability for a little while after the contents of the body had been emptied, and continued a riggling, uneven motion. 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 cilire, 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 VOL. Hr. c |