PHY 



OR, BOTANICAL DICTIONARY. 



PHY 



299 





texture vary according to the different species. They are 

 Resinous, in many species of Fir, &c. ; Gummy, in fruit-trees 

 and some species of Mimosa; Lymphatic, in almost all plants. 

 The colour of the juices found in the cellular texture, is also 

 very multifarious. The sap likewise varies in colour: It is 

 White, in Euphorbia, Papaver, Leontodon, Pinus, &c ; Yel- 

 low, in Chelidonium; Red, in Rumex sanguineus, Dracsena 

 Draco, Pterocarpus santalinus, and Calamus Rotang ; Blue, 

 in the root of Pimpmella niyra; Green, in some Umbellatae; 

 Colourless, in most plants. The juices in fruits are known to 

 be of all colours. Rafn discovered a great analogy between 

 the sap of plants and the blood of animals. He detected 

 with a microscope magnifying 135 times, in the lymph of Eu- 

 phorbia pahtstris, round globules, like those in blood, swim- 

 ming in a fluid somewhat more clear, but not so clear as 

 water. Fontana observed the same in the sap of the Rhus 

 toxicodendron. Rafn, however, found in the Euphorbia, 

 besides the globules, prisms, which appear in Euphorbia pep- 

 lus, helioscopia, esula, cyparissias, and lathyris, though 

 somewhat different. In no plant but the Euphorbia and 

 Hura crepilans could he detect the prisms. One drop of 

 lymph of Euphorbia Canariensis, Caput Medusa, Chara nerii- 

 folia, had one or two prisms at most. Alcohol congealed the 

 juice of the Euphorbia, and formed a great deal of fibrous 

 matter. Vitriol also converted it into fibres, which however 

 were not so thick. The sap of Chelidonium consisted of no- 

 thing but closely cohering globules. In the colourless vege- 

 table juices, even in them which are seemingly moist, the 

 same globules appeared. A proof that the sap of some vege- 

 tables, for instance, the Potentilla anserina, is not, as Plenk 

 supposes, merely impure or unfinished water. Rafn found 

 in those plants which have much cellular texture, e. g. the 

 Musa paradisiaca, Strelitzia regina, the globules smaller 

 and less frequent than in the species of Euphorbia. The 

 apertures which are discovered between the lymphatic vessels 

 on the epidermis of plants are connected with the cellular 

 texture, and by the operation of the rays of light may be 

 opened and shut, and, according to Hedwig, are designed for 

 transpiration. Secondary vessels, which Schrank has amply 

 described, are hairy or bristly formed elongations of the epi- 

 dermis, of a complicated nature, hollow within, and are con- 

 nected too with the cellular texture. Some suppose that they 

 are created for the purpose of suction. Soft down, and the 

 fleecy covering of several seeds, appear to be only protracted 

 secondary vessels. The .vegetable Jibre, is a thin filiform 

 body, found in bundles, and has apparently no cavity within; 

 it is encircled with a cellular texture, which forms around 

 it a particular kind of sheath. That this single fibre of vege- 

 tables may consist of several, will not be disputed ; but to 

 resolve it into its individual parts, and to demonstrate the 

 most simple fibre, will probably continue to baffle our 

 researches. Rafn is much inclined to consider the vegetable 

 fibre as a particular and original organ, similar to the mus- 

 cular fibre o animals. Hedwig, on the contrary, supposes 

 it to be an obsolete constipated vessel. A great deal might 

 be advanced in favour of this last opinion ; for, as plants 

 annually, form new vessels, the number of fibres appears to 

 be increased by the old vessels. Notwithstanding, however, 

 it is alleged, by others, that fibres at their very origin have 

 been found constipated between the leaves of herbs. But 

 even should future observations lead us to regard this fibre 

 as a constipated vessel, still it appears certain that the skin 

 of the vessels themselves is of a muscular nature, as it is capa- 

 ble of contracting and expanding in a regular manner. Glands, 

 are in vegetables of multifarious situation and figure. Though 

 their internal structure continues, upon the whole, pretty 



VOL. II. 91. 



equal, they have not the most distant resemblance to animal 

 glands, and their having the same designation is entirely 

 owing to their being more or less roundish elevated bodies. 

 They are found internally and externally, according to their 

 situation. Internally, they are situated in the cellular texture, 

 or fleshy part of vegetables, and are found of a globular, 

 somewhat oblong and lenticular figure, in the middle or the 

 partitions of the cells, as also in the inner bark. Externally, 

 they are discovered in all parts of vegetables, either half 

 sunk in the cuticle, rising to the surface, or possessed of 

 stalks. They have then a very extensive variety of shape; 

 sometimes they are perpendicular, oblong, or depressed ; 

 sometimes very elevated and pointed, having their upper 

 part furnished with a small hole, or even surrounded with an 

 elevated margin. The different species of glands are exceed- 

 ingly numerous, and may be distinguished by calculating all 

 the varieties. Being sometimes more, sometimes less obvious, 

 they are, in the Hypericum perforatum, considered merely 

 contrary transparent particles, which are visible when exposed 

 to the rays of light. In the Hypericum montanum, they are 

 easily observable by their brown colour; and in the genera 

 Passiflora, Mimosa, and Croton, their magnitude is some- 

 times so very considerable, that the mere touch of them 

 serves to convince us of their existence. Glands consist, 

 internally, of a dense cellular texture, which is too dense in 

 proportion to the middle. Immediately under their skin, 

 and upon the vertex, they contain a matter more or less 

 coloured, odoriferous, or insipid, according to the variety 

 of the plants. The glands which are situated in the interior 

 of the plants, have no connection with the vessels; but 

 glands which are evidently situated on the outside of vege- 

 tables, have spiral vessels pressing forward to their centre, 

 and then returning in a retrograde direction. The anasto- 

 mosis of vessels in the vegetable kingdom is totally different 

 from what it is in animals. The adducent, reducent, and 

 air vessels, uniformly run in bundles through the vegetable 

 body more or less perpendicularly ; these separate into smaller 

 bundles, which unite with the nearest body, and out of these 

 still smaller ones adhere to a greater body; so that, upon 

 the whole, by the separation and union of the bundles, a 

 reticular appearance is produced. Lymphatic vessels, how- 

 ever, run singly, and anastomose like the vessels of animals, 

 their boughs really uniting with the other branches. 



" After these general discoveries made by physiologists in 

 the vegetable kingdom, it will be proper regularly to examine 

 the most remarkable phenomena which have been observed 

 in vegetables from their origin out of seeds to their decay, 

 and briefly to comprehend the inferences which hitherto 

 have been drawn, that the recurring scenes of life and death 

 in all their various forms may thus be more fully elucidated. 

 The structure of the seed has already been explained, and 

 we know that it serves the same purpose as the egg of ani- 

 mals, i. e. it contains the rudiments of a new being perfectly 

 similar to its parents, and waiting only for a favourable 

 opportunity of being evolved. All plants are propagated by 

 seeds ; and we may boldly exclaim with Harvey, " Omne 

 vivmn ex ovo." It cannot indeed be denied, that they have 

 not been found in all plants; but their existence in Mosses, 

 Liverworts, Mushrooms, and many others, where formerly 

 it was obstinately disputed, has, by the unwearied diligence 

 of philosophers, now been completely ascertained ; and we 

 have no doubt that they wiH one day be observed in those 

 where at present they are merely supposed to exist. Agree- 

 ably to the eternal and immutable laws of nature, we observe, 

 just as in the animal world, the same species arising always 

 from the seed ; and no other vegetable can ever issue from 

 4G 



