OCR Text |
Show 116 BAHIA BLANCA. Aug. 1833. eggs. Numerous Lamellicorn and Heteromerous insects, the latter remarkable for their deeply sculptured bodies, were slowly crawling about; while the Saurian tribe, the constant inhabitants of a sandy soil, darted in every direction. During the first eleven days, whilst nature was dormant, the mean temperature taken from observations made every two hours on board the Beagle, was 51° ; and in the middle of the day the thermometer seldom ranged above 55°. On the eleven succeeding days, in which all living things became so animated, the mean was 58°, and the range in the middle of the day between sixty and seventy. Here then an increase of seven degrees in mean temperature, but a greater one of extreme heat, was sufficient to awake the functions of life. At Monte Video, from which we had just before sailed, in the twenty-three days included between the 26th of July and the 19th of August, the mean temperature from 276 observations was 58°.4; the mean hottest day being 65°.5, and the coldest 46°. The lowest point to which the thermometer fell was 41°.5, and occasionally in the middle of the day it rose to 69° or 70°. Yet with this elevated temperature, almost every beetle, several genera of spiders, snails, and land shells, toads, and lizards were all lying torpid beneath stones. But we have seen that at Bahia Blanca, which is four degrees to the southward, and therefore with a climate only a very little colder, this same temperature with a rather less extreme heat, was sufficient to awake all orders of animated beings. This shows how nicely the. required degree of stimulus is adapted to the general climate of the place, and how little it depends on absolute temperature. It is well known that within the tropics, the hybernation, or more properly estivation, of animals is governed by the times of drought. Near Rio de Janeiro, I was at first surprised to observe, that, a few days after some little depressions had been changed into pools of water by the rain, they were peopled by numerous full-grown shells and beetles. Humboldt has related the strange accident of a hovel having been erected over a spot, where a young crocodi'le lay buried in Aug. 1833. SEA-PEN. 117 the hardened mud. He adds "Th I . mous boas; which they call u·. e ndmns often find en or- . JI, or water serpent · h s. am. e lethargw state · T o ream.m ate the tl s, m t e Irntated or wetted with water." m, ley must be I ';ill only mention one other animal . to VIrgularia * a ki'nd f ' a zoophyte alhed ' o sea-pen It · straight, fieshy stem w'th lt . consists of a thin, . ' I a ernate rows of 1 · side, and surrounding an e1 a stw. ston · · poI Y PI on· eac. h length from ei'ght · h Y axis. t vanes m me es to two f, t Th extremity is truncate b ee · . e stem at one vermiform fiesh ' ut at the other IS terminated by a compartments . Indapi. petnhdage, which is separated into two contained Th' e t n e. se ' s.m all' y e1 1 ow, sp h erw· al ova are · s ony axis whwh · may be traced at this e t . . gives strength to the stem, granular matter Th' x redm ity mto ame re vesse l fill ed W.i th · Is un eveloped f · transparent elast' . . bl por IOn IS enclosed in a ' w, Irr1ta e bag c t · · :fi . . ;::J i~i~!:c~;:ulation of particle~~0'::;',;';,~ :ee:d ~:h~~~ pendage At 1 e compartments of the fleshy terminal ap-seen, pr~jectin;~i~:t::u~~~dre~s of these zoophytes might be a few inch b e, With the truncate end upwards touched o;s a 1 ove the surface of the muddy sand. Whe~ with force pu led, they drew themselves in, suddenly and ' so as nearly or quit t d' action, the hi hl 1 . . e 0 Isappear. By this t . g y e astic axis must be bent at the lo ex remity wh · . wer ima . .' . ere ~t Is naturally slightly curved. and I to ~me It ~s by this elasticity that the zoophyte i; enabled nse agam through the mud E closely united to its brethren h . d' ~ch polypus, though tentacula Of these . . ' as a Istmct mouth, body, and many th~us d polypi, m a large specimen, there must be that they han s ; yet we see that they act by one movement . obscure cir::~t~: .ce~~~altha~st~onnected with a system of organ distinct from 'th a . e ova are produced in an e separate mdivid 1 W be allowed to ask what . . di . ua s. ell may one other observatio~ o tihs' an m VIdual? I will add only one from the fi h n Is zoophyte · The caV·I t·ie s leading es y compartments of the extremity, were filled • I be r I eve "rru·- gutarz.a Patagonica of D'Orbigny. |