Page:Cyclopaedia, Chambers - Supplement, Volume 1.djvu/791

 GEN

GEN

increases it by telling us, his patient's Wife had the character of a very virtuous woman* See Phil. Tranfi N°. 480. p. 218.

There is no part of the hiftory of animals fo difficult to acaount for as their generation, in many particulars, and this is in none fo abftrufe, as in thofe which are produced in places to which there is no vifible way for them to arrive. The animalcules difcovered by Lewenhoek, in the femert mafculinum of animals, and the worms in the hu- man bowels are of this kindi The firft of thefe are too minute for our obfervation in regard to the clearing of this point j but as to the others, Vallifnieri has proved, that they are not produced from the eggs fwallowed down our throats in our drink or otherwife, but that they really do propagate their fpecies within us, and are owing to parents of the fame kind hid in fome parts of our inteftines. Redi has given fuch defcriptions of the lumbrici rotundi, or com- mon worms, that the thing is rendered pail all doubt in regard to them ; and this author taking up the fubjecT: where he dropped it, has proved, as much in regard to the taenia, or tapeworm.

The bowels are evidently the true arid proper feat and habi- tation of. thefe creatures, but they are alfo fometimes voided by urine, and thence conceived to have lived in the urinary paffages. Vallifnieri gives an account of a worm in the form of a ferpent voided by urine by a pricft, from one Landus ; and from Alghifi another cafe of great numbers of worms of the ftze and fhape of barley corns, voided in the fame manner after terrible pains. Our tranfactions alfo give an account of a large and long Worm, taken out of the penis of a youth by a furgeon of reputation. It is pof- fible that worms different from thofe ufually found in the body, may be fometimes generated there, but as to their in- habiting the urinary paflages, there is great reafon.to fuf- pect the fact. That they have been voided by urine is certain, but in perfons who have died foon after, and been diflected, it has been found that the colon has been exuleerated, and that thefe creatures had eaten their way from thence into the bladder-; and this is probably the cafe in all thofe ftorics, where the fact is certain. And the opinion of Vallifnieri as . to the reft is, that they were concreated with the human frame, and that our bowels are their natural and proper nidus. Vd- Ujnieri Obfer. Med.

The polypus, or polype, being neither male nor female, \ but producing its young, as plants do their moots, only that at laft the young polypes drop from their parent, fhews a remarkable anology between animal and vegetable nature. See Polype.

Mr. Demours a affords us another fact to illuftrate this ana- logy. It is in the act of propagation of water falaman- ders, the male of which has no penis, but fquirts out his femen at a little diftance from the female ; and though it could not be obferved that any of it is received into her body, yet her ova are. fecundated. a Obfervat. concern. L'Hi/l. naturelle.

Some animals may be generated from the cuttings, or pieces of another of the fame fpecies, in the fame manner as trees and plants are produced, by fetting fmall pieces of the fame plant. See Polype. Generation of plant!. The generation of plants bears a near analogy to that of fome animals, especially fuch as want local motion, as oifters and fome other {hell nfh. The flower is the container of the parts of generation, and each performs its peculiar office for the propagation of the fpecies. The flower of a lilly, for inftance, confifts of fix petals, flower leaves, from the bottom of which, at the middle arifes a kind of tube, called the piftil, and round thi there are difpofed feveral fmall threads called the ftamina or chives, which arife alfo from the bottom of the flower, and terminate at their tops in fmall bodies called the apices. which contain a fine duft called the farina. Miller's Gard Diet.

This is the general ftrudture of flowers, and though in many, fome of thefe parts feem wanting ; yet probably they are there, only lefs apparent. The fruit is ufually at the bafis of the piftil, fo that when the piftil falls with the reft of the flower, the fruit is feen in the place of it, though in fome this is not the cafe, but the piftil itfelf becomes the fruit. The petals feem only an outer covering to defend the piftil and ftamina, and the duft' which the apices at the ends of thefe are full of, was by many great men believed to be only an excrementitious matter feparated from the plant, by the chives, which they fuppofed tubes deftined to carry off this abundant nutriment from the fruit. Later difcoveries however have fhewn this to be a very elTential part of the flower, and to ferve the office of the male fperm of animals, and that the piftil is properly the female organ of generation. The feeds which come up in their proper involucre, feem of the nature of the unimpregnated eggs of animals; alfo that the farina feminalis, or duft contained in the apices, is a congeries of plantules, each of which is to be lodged in one of thofe feeds, which are only a proper matrix for its recep- tion: ;, that the ftyle or upper part of the piftil is a tube deftined to conyey thefe feminal. plant* into the uterus,, or

bottom of the piftil where thefe feeds are lodged ; and finally it appears, that the vaft quantity of this farina is only be- cause of the multitudes that muft mifcarry, for one that finds its way into this narrow paflage.

To exemplify thefe conjectures by obfervation. It may be feen that in the crown imperial, the uterus, or Vaf- culum feminale of the plant, ftands upon the center of the flower j and from the top of this arifes the ftyle, the vafcu- lum feminale and ftyle together making the piftil. Round this are placed fix ftamina, the apices of which are fo art- fully fixed, that they play about with every wind;. and are in height almoft equal to the ftyle, round about which they are continually in motion, and which in this plant is miini- feftly open at the top, and hollow all the way down ; and to this it muft be added, that on the top of this ftyle there is a tuft of pinguid villi, or fmall tendrills, which feem de- ftined to catch hold of the farina, or male duft, as it is dif- lodg'd from the apices when they burft, and from thefe it may very eafily find its way through the hollow to the feeds it is deftined to impregnate. Miller's Gard. Diet, The tube or ftyle of the piftil always dies away as foon as the apices have difcharged all their powder, having then fcrved the purpofes it was defigned for.

The feminal plant is always lodged in that part of the feed which lies neareft the aperture of the tube, through which this farina ie conveyed ; and in beans there is an evident perforation to be difcovered by ordinary glafles juft above the eye, which probably has been the paflage by which the plan- tula feminalis entered. In thefe and the other leguminous plants alfo, if we carefully take off the petala of the flower, we fha.ll difcover the> pod clofely covered by an enveloping membrane, which near the top feparates into feveral ftamina, each loaded with its apex and farina, and thefe ftamina are all bound clofely to that brufh which fhews itfelf at the end of the pod.

In rofes there ftands in the middle a column confifting of many tubes, which though clofely clung together, yet are ea- fily feparable, and each leads to its particular cell, the fta- mina being in great abundance placed all round the orifices of thefe tubes. In ftrawberries and rafberries, the hairs growing on the outfides of thofe fruit are fo many tubes leading to the feeds, and in the firft opening of the flowers of thefe plants, thefe hairs ftand in a thick wood as it were at the bottom of the flower, and are every where Unrounded by ftamina with apices on their tops ; and it is not till after thefe apices have difcharged their farina, that the fruit fwells out of the hufk. In flowers which' naturally hang down, as the imperial crown and the like, the piftil is much longer than the ftamina, that it may receive the farina as it falls from the apices.

Mr. Geoffroy obferved, that the cutting off the piftil of a flower before the apices were ripe, always made the fruit abortive, and the plant barren for that feafon. In fome plants, whether male and female flowers ftand on different ftalks from the fame root, or on different plants of th« fame fpecies, the wind is the vehicle of this farina ; and if it does not reach the female flowers, they ever remain barren. Miller's Gard. Diet.

Generation of plants from pieces or cuttings of the fame plant. See Pieces.

Generation, in mathematicks, is ufed for formation or production. Thus we meet with the generation of equa- tions, curves, folids, &c.

Generation ofjione. See Lithogenesia.

GENERICAL name, in natural hiftory, the word ufed to fig- nify all the fpecies of natural bodies, which. agree in certain effential and peculiar characters, and therefore all of the

\ fame family or kind ; fo that the word ufed as the generical

\ name, equally expreffes every one of them, and fome other

1 words expreffive of the peculiar qualities or figures of each are added, in order to. denote them fingly, and make up what is called the fpecific name.

Thus the Word rofa, or rofe, is the generical name of the whole feries of flowers of that kind, which are diftinguifhed by the fpecific names of the red rofe, the white rofe, the apple rofe, csV. The ignorance of former ages in the true principles of natural hiftory, has occafioned the bodies, which are the objects of it, to be arranged into very unnatural fe- ries under the name of genera ; and thefe have been called by names as improper, as the characters they were diftinguifh- ed by. Linnaeus has done a great deal in the exploding the bad gemrkal names in Botany, and Artedi has applied his rules about the formation of thefe names with very little difference to the fubjects of ichthyology. See Botany. Many of the generical names of fifties, till the time of this author, were fo barbarous and obfeure, that it was not eafy to trace them to their original ; or to find whether they were truly Teutonic, Englifh, Dutch, Swedifh, French, Italian, Spanifh, Portuguefe, Latin or Indian. The ignorance of the writers on thefe fubjects, or their too fcrupulous adhe- rence to the cuftoms of their predeceffors, feem to have been principally the caufes of this, and often an entire neg- ligence. Artedi'* rules,for generkd najnes for fifties are thefe.

Whatever