47

the

of nl Vegrtables. —A eertain degree of heat promotes all the vital processes

^ plants. It accelerates germination, the growth and development of all vegeta-ciui u rgaUS i! inflorescence ' fecundation, and the ripening of the fruit; and itL../ ens the movements of parts susceptible of motion. Too elevated a tem-

dn[i atUr n'/ accom P anied with dryness, deranges the health of plants. (Decs°»e, Physiologie Vegetale, tom. iii. p. 1098.) An intense heat decompos

vegetable tissu

ecan-oses

diir' U Cmd ° ther Animals -~ k - eertain degree of external heat (different in

nerent beings) promotes the vital manifestations of animals, and hence we

eiMfflmate it an excitant or stimulant. Its prolonged Operation, however,

tollowed by debility and exhaustion proportionate to the previous excite-

Tl • a

eff '.iflnence of tropical heat on the human species furnishes an illustrative example of the

ects just mentioned. It is well known that the mental powers of children are iocvelop " ^^^^^^^^^^™

ll >e lar,

Ped, and the sexes arrive earüer at puberty, in warm Lhan in cold eountries. Moreovcr,

uor, indolenee, and relaxed fibres, so commonly observed in the inhabitants of tropical

infl" a CS ' are P rol)a bly to be aseribcd, in a great measurc, to the exhausting and enervätinff■wueneeof external heat.

an 1 le ^ ecls °f topical heat are first, a Sensation of warmth, redness, turgescence,the a S ht au Smentation of temperature of the part heated. The diameters ofred bl^rirUt^"^ 8 ' 1 ^ vessels expand under the influence of calorie, and thus theau °°d-disks are enabled to enter tubes previously impervious to them. The•senpp % Y om me of the part arises, therefore, in a great measure frorn the pre-solid T fl n( ? rease(] quantity of blood; but in part also Crom the dilatation of thebe and fluids caused by their augmented temperature. The living tissues» nr \ „j 6 '. nor ? re laxed, soft, and flexible, under the influence of a moderate lies

and 1 1 ' * waA -CU, S'OU, Ü11U 11ÜA1UIC, UIJUCJ 111V3 LUUUCUW: Ul d IllUUCliHU lieat,

A still ~- V1 °lent degree of heat causes burning pain, redness, and vesication.

Portion" 110 / 6 * ntense heat destroys vitality and Organization. Whenever a largecortstitut l ^ 6 ? ur *" ace °f tne l30t 'y 1S destroyed (as in bums and scalds,) greatvouq ai !° na ^ disturbance, or even death, resulls from the shock given to the ner-"= *y stein.

■\vith n 1 W e D °dy be subjeeted to an elevated temperature, not incompatiblethe or(r° e< ^ ^ e ' * ts e ^ ecls are manifested first in, the vascular System, and incornes?, connecte d therewith. The superficial vessels erdarge; the skin be-aninial h .' anc ' tne pulse quieker and füllen respiration more frequent; thevapour ' eat ' S au g |n ented; and the expired air is hotter, and more loaded with

TlP'oying tl

the

"'S influence of heat, on the vascular System, points out the impropriety of cm.

e,r «ulation

•ifi^ 0 " 1 '" 'nflammation or congestion of the Organs (heurt and lungs) engaged in

other caseT' U r°[ tlle b ' oocl ' '" dilalations of the heart; in arieurism ; in apoplexy; and many~ nich will readily suggest themselves.

and liquid exlla lation (first of insensible and vaporous matter, then of visiblerapid conv^ 6 ^ an ^ au g mente d secretion of the periphery soon sueeeed. Theattended wrrtf 1 ^ 1 ° f a li( l u ' d int0 an aeriform fluid (insensible Perspiration) ise xternal h t produetion of cold; and thus animals are enabled to counteractto a tenm ^ t0 ma ™ ta ™ nearly tn eir original temperature, when exposedcreased p e eratUre . c °nsiderably higher than that of their own bodies, by the in-mination t rS fF lrati ° n wmcu tne y su fl* er under these circumstances. The deter-are attendel ^ ? umice > and the increased transpiration and secretion of the skin,nal Organs ^tm a contem P oran eous diminution of activity in some of the inter-are diminfsb l • S ' tne secreu °ns of the kidneys and the mueous membranesthe skin m c °nsequence of the increased secretion and exhalation of

The mutuallv anta s of Uio secretions f T n ' m £ innuen <=e of determinatus of blood to different parts—as well' ot different tissues—is a circumstance the fecowledge of which is of"-reat