Page:Cyclopaedia, Chambers - Supplement, Volume 2.djvu/461

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meht proves that it is poffible tb touch the branches in filch a manner, as to affect them only, and make them apply ihemfelves to the trunk, while the leaves feel nothing of the touch : but this cannot be, unlefs the branches are fo difpofed, as that they can fall to the trunk without fuffer- ing their leaves to touch any other part of the plant in their paffage; becaufe if they do, they immediately become af- fected. Winds and heavy ra'ms caufe the fenjitive plants to fhut up their leaves, while eafy fnowers do not at all afreet them : it is plain hence, that the agitation of the plant by the wind, and the ftrokes given by the large and hafty drops of rain, are what caufe the contraction. By whatever accident the plant has been made to clofe its leaves, it always regularly opens them again afterwards. This however requires different times, according to feveral circum- stances, as the time of the day, the feafon of the year, and the more lefs or vigorous and healthy ftate of the plant : fometimes this is done in ten minutes, fometimes it requires half an hour. And the manner is not lefs different than the time; for fometimes the leaves unfold themfelves firft, and fometimes the brandies, whereas fometimes all is done at once, and the whole plant feems in motion at a time. In endeavouring to account for the motions of this plant, thefe gentlemen have conjectured that they are performed by means of a fort of very nice and fine hinges, which com- municate one with another by means of very minute and flender cords, which occafion them to act as we fee when the plant is fufHciently difturbed, and thefe cords fliaken ; and what gives a ftrong probability to this conjecture is, that the decayed and dying leaves of the plant perform this motion as regularly and vigoroufly, as thofe which are frefh and full of juice. It feems plain, that while the juices are evaporating, and the parenchymatous fubftance of the leaves drying up, thefe more folid parts, the lines and cordages, retain their figure ; and confequently, if it is by means of thefe that the motion is always performed, it will be as well performed in thefe as in the frefher leaves ; which could not be the cafe, were it owing to the juices. The natural opening and shutting of the leaves of this plant at night and morning, are not fo fixed but that they are va- riable alfo, according to circumftances of place, tempera- ture, &d In the month of Auguft a fenjitive plant was carried in a pot out of its ufual place into a dark cave, the motion that it received in the carriage fhut up its leaves, and they did not open till twenty four hours afterwards. At this time they became moderately open, but were after- wards fubject to no changes at night or morning, but re- mained three days and nights with their leaves in the fame moderately open ftate. At the end of this time they were brought out again into the air, and there recovered their natural periodical motions ; fhutting every night, and open- ing every morning, as naturally and as ftrongly, as if it had not been in this forced ftate ; and while in the cave, it was obferved to be very little lefs affected with the touch than when abroad in the open air.

Repeated experiments have proved, that it is not the light of the day that opens the leaves of this plant, nor the darknefs of the night that clofes them; neither is it the alternate warmth of the day, and cold of the night, that have this effect, fince it fhuts in nights which are much warmer than the days often are in which it opens; and the encreafing the heat of the place in which it is kept, and marking the encreafe or decreafe on the thermometer, have been found to have not the leaft effect, as to its fooner or later .opening , or fhutting its leaves. The moft probable conjecture feems, that it is not great heat, or great cold, fuch as it can bear, that bring on this effect, but the fudden change from one to the other; and this is confirmed by this experiment, that if one of thefe plants be raifed under a glafs bell, or cafe, and the bell or covering be taken off, it immediately clofes, even though it be in the middle of the day ; and this is alfo obferved, that the more open or expofed theplant ftands, the more ftrong and lively are its fhutting and opening ; and that they are moft obferv- able in fummer, and much lefs fo, when it is kept in a clofe ftove in winter.

The great heats of fummer, when there is open funfhine at noon, affect the plant infome degree like cold, caufing it to fhut up its leaves a little, but never in any very great degree. The plant, however, is leaft of all affected about nine o'clock in the morning, and that is confequently the propereft time to make experiments on it. A branch of the fen/Ithe plant cut off, and laid by, retains yet its pro- perty of fhutting up and opening in the morning for fome days ; and it holds it longer if kept with one end in water, than if left to dry more fuddenly.

The leaves only of the fenjitive phut fhut up in the night, not the branches, and if it be touched at this time, the branches are affected in the fame manner as in the day, fhut- ting up, or approaching to the ftalk or trunk, in the fame manner, and often with more force. It is of no cpnfe- quence what the fubftance is with which the plant is touch- ed, it anfwers alike to all ; but there may be obferved a little fpotj diftinguifhable by its paler colour in the articulations

of its leaves, where the greateft and niceft fenfibility is evi- dently placed.

The fenjitive plant, plunged into water, immediately clofes its leaves, which is partly owing to the touch, partly to the coldnefs of the water • afterwards the leaves expand againj and if they are then touched, clofe again as before* as if" in the open air, only that they do it with lefs force. If the end of one of the leaves be burned with the flame of a candle, or by a burning glafs, or by touching it with hot iron, it clofes up in a moment, and the oppofite leaf does the fame, and after that the whole feries of leaves on each fide the rib, then the rib itfelf, then the branch, all do the fame, if the burning has been in a fufiicient degree. This proves that there is a very nice communication between all the parts, of the plant, by means of which the burning, which only is applied to the extremity of one leaf, diffuses its influence through every part of the fhrub. If a drop of aquafortis be carefully laid upon a leaf of the fenfitive plant, fo as not to fhake it in the leaft, the leaf does not begin to move till the acrid liquor corrodes the fubftance of it; but at that time, not only that particular leaf, but all the leaves placed on the fame rib, clofe them- felves up. The vapour of burning fulphur has alfo this ef- fect on many leaves at once, according as they are more or lefs expofed to it; but a bottle of very acrid and fulphure- ous fpirit of vitriol, placed under the branches unftopped, produces no fuch effect. The wetting the leaves with fpirit of wine, has been obferved alfo to have no effect, nor the rubbing oil of almonds over them ; though this laft applica- tion deftroys many plants.

A branch of the plant was cut away longitudinally, till only a third part of the fubftance remained, yet it communicated the effects of the touch, in the fame manner as before, to thofe branches which arofe lower on the fhrub. The tranf- pi ration of the plant being retarded, is of no effect as to its periodical opening and clofing; for one kept under a clofe glafs bell fhuts and opens as regularly, night and morning, as when it ftands in an open green-houfe. A branch of ft put into the exhaufted receiver of an air-pump, is found to have its force of opening and clofing up much impaired, but not wholly taken off. Mem. de 1'Acad. des Scienc. Par. 1 7 36.

SEPHIROS, a word ufed by Paracelfus, and his followers, to exprefs a fort of dry and hard impoftume, or kind of fpu- rious fcirrhus.

SEPHIROTH, a Hebrpw word fignifying brightnefles ; and the cabbalifts g[ve the name of fephiroth to the moft .fecret parts of their lcicnce.

The knowledge of the fephiroth is not acquired but with much itudy and labour, and is the higheft ftep of the con- ternplative theology. They reckon up ten fephireths, which are fometimes reprcfented by ten different circles, included in each other ; and fometimes by the figure of a tree, pretty much like what, in the fchools, they call Porphyry's tree, to fhew the different categories of ens or being. Calm. Diet. Eibl. in voc.

SE PIACE, in the Italian mufic, fignifies that the part it is joined to may be repeated, or not, at pleafufe.

SEPS, in zoology, the name of a very peculiar animal of the lizard kind, but feeming as if of ;a middle nature between that genus and the fnakes, and appearing rather a ferpent with feet than a lizard. See Tab. of Quadrupeds and Ser- pents, NP31.

It is a fmall fpecies ; its body is rounded, and 1 its back va- riegated with longitudinal lines of blacji. Its eyes are black ; it has ears, and a fmall and very flender tail; What ap- pears moft fingular in it is, that it has four legs with feet, divided into toes; but thefe -are wholly ufelefs to the crea- ture in its motions, and not at all affifting it in walking. The firft. pair are placed very near the head, the other by the anus. The fcales are laid in a reticulated manner ; they are of an oblong figure, approaching to a rhomboides, and laid longitudinally. Its belly is white, with a flight caft of blue, and it has noftrils near the end of the fnout. Cb- lumna took five living young ones out of the body of one of this fpecies, fome of which were> included in membranes, and others loofe, as -is. the cafe in the feet us found in the viper. Ray's Syn. Quad, ^.-272.,

The bite, of the feps is faid to occ,afion an inftant putrefac- tion of the flefh of the whole body.

SEPT ANA, a word ufed by the antient phyficians for a fep- tenary fever, or. one that performs its regular period in feveri days.,

SEPTARI^E, in natural -hiftory, the name of a large clajs of foffils, called by fome Indus Helmontii, and by others the waxen veins. They are defined to be foffile bodies not inflammable, nor foluble in water, naturally found in loofe detached maffes of a moderately firm texture, and dufkybue; divided by feveral y^pta, or thin partitions, and compofed of a fparry matter greatly debafed by earth, not giving fire with fteel, fermenting with acids, and in great part dillolved by them, -and calcining- in a moderate fire. Of this clafs there are two diftinct orders of bodies, and under thofe fix genera. The feptarits of the firft order are

I thofs which, are ufually found in large maffes, of a Ample

' uniform