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means, fubscribe. He fay's, (p. 228.) * If we put the feeds of an annual plant into the ground, plants grow from them, which foon flower, produce seed, and then die.'- The buds of trees and shrubs are to be considered as annual plants; for, as faon as they have bloßomed and fhed their feeds, they decay entirely." This is certainly not the case ; for the far greater number of the buds of trees and shrubs, produce branches which remain for years.
We fball give what he says (p. 229.) on the chemical principles of vegetables, as a specimen of the method in which he treats his fubječt.
The chief vegetable principles are, "1. Caloric, is present in all parts of vegetables, and conftitutes their temperature when free.
i 2. Light, is found in the oils and other indammable vegetable fub£ances.
• 3. The ele&ric Auid, shows itself by various electrical phenomena observed in plants.
* 4. Carbon, is the chief conftituent part of all vegetables.
* 5. Hydrogen, this may easily be obtained in a gazeous form, com. bined with caloric, from all liguminous plants.
16. Oxygen is, we fall soon find, evolved by the rays of the sun. Part of it, however, is combined with acidifiable bases, and forms vegetable acide.
7. Azote, is exhaled by plants in the night : the greatest part of it, however, is in a combined ftate. Whether' azote belongs to the fimple subftances (elements), or, as Goettling fupposes, is a compound of oxygen and light, we must leave to the future decision of chenils. At present, we shall confider it as a fimple subttance.
* 8. Phosphorus, occurs in plants of the 15th class, and in the gramina. Its existence manifeftly appears, by che shining of old rotten woad, the root of the common Tormentilla recta, and rotten potatoes, Solanum tuberosum.
• 9. Sulphur, in form of acid combined with oxygen, is met with in many plaots, either with potaso forming a sulphat of potass, or with foda, as fulphat of soda. Even in substance, sulphur has been found in the roots of the Rumex patiearia. After they were cut down, boiled, and scummed, sulphur appeared in the scum when left to settle.
ini. Sada, is peculiar to almost all plants growing on ka shores or in falt marshes.
• 12. Silica, is found in the stem of the Bambusa arundinacea, and in the common reed, Arundo phragmites. It is supposed to exist in the alder, Betula alnur, and birch, Berula alba, as their wood often enits (parks when under the hands of the turner.
• 13. Alumina, it is said, has been found in some pants.
• 14. Magnelia, some philosophers think, they har: ret with likewife.
115. Barytes, is chiefly obvions in graffes.
• 16. Lime, is found in almoft all vegetables, most frequently in Chara tomentofa, a pound of which is said to contain five ounces of it.
! 17. Iron, is detected in the ashes of most plants. • 18. Manganese, has likewise been sometimes found in plants.' There is added in a note, • If some have detected gold in the vine, Vitis vinifera ; oak, Quercus robur ; hornbeam, Carpinus betulus; or in ivy, Hedera helix ; and tin in Spanish broom, Spartium junceum ; it seems merely to have been ac. cidentally, as their presence has been stated as impossible by late experiments. Of the above principles, No. 1–7, and 10, 16 and 17, are found in all plants; the rest only in some. The Fungi, especially the genera Petziza, Octofpera, and Byssus, have, according to the latest researches, not a reitige of lime.
. All the now enumerated principles which have been found in ve. getables, belor:g, as far as chemical knowledge has advanced, to the elementary or simple substances. The vital power produces, by mixing them, new formed substances.'
These, however, we must omit for want of room. Among these new productions he mentions Wax. His words are—(p. 231.)
"Wax is likewise found in the fruits of some plants, ex. gx. of the laurel (Laurus nobilis), and of the Myrica cerifera and others. We have it in the pollen of all flowers ; and accordingly bees prepare their wax from it.'
The substance obtained from the Myrica cerifera is by no means the same with bees wax; nor do bees form their wax from the pollen of flowers. From a set of comparative experiments insti. tuted by Dr Bostock on myrtle wax, i.e. the substance obtained from the Myrica cerifera, bees wax, spermaceti, adipocire, and the crystalline matter of biliary calculi, * it appears that myrtle wax differs from bees wax in specific gravity and in its habitudes, with a variety of reagents. The ingenious and decisive experimients of M. Hubert, have proved, in a very satisfactory manner, that bees form their wax from honey, or any saccharine matter, and that they collect and store up the pollen of flowers, only as food for their larvæ.
It would have been satisfactory to many of his readers, had he mentioned the experiments on which some of his assertions are founded; or, if this would have occupied too much room, he might have mentioned the authors from whom he had drawn his information. He has abridged the chemical part very much where facts might have been adduced; and extended other parts where nothing but vague hypotheses can be advanced.
After giving the chemical principles of plants, and the substan
* Vide Nicholson's Journal for March 1803.
ces formed by their combination, he proceeds with the different vefsels of plants, viz. air, and lymphatic vefsels, the cellular texture, the fap, and their transpiring pores. Where he treats of these, we find, in page 243, a blunder which must have escaped either the author or translator: cubic has been used instead of Square. He says, ' Hedwig counted in the Lilium bulbiferum, in one surface of a single leaf, 577 apertures in one cubic line. A cubic foot would therefore, according to this observation, have about 998,145 apertures.' The calculation too, if it has been made according to the table given in page 10, is incorrect. After discussing the temperature and phenomena of the germination of plants, he proceeds to the structure of their different parts. In mentioning the structure of the bud, p. 273, he says; · Each bud unfolds a branch, with leaves, which, at the base of each petiole, again produce buds. In this manner their growth continues. But this evolution of buds from buds, would continue without stopping, were it not so regulated that each bud, as foon as the blossoms and fruits are perfectly formed, decays.' We confess we do not understand what he means by this, unless he means to affert what has no foundation in nature. He advances something to the same purpose, when treating of the structure of vegetables, near the commencement of his physiology ; against which we have already entered our protest. We shall now give our reafons. Every branch that proceeds from a bud, produces one or more buds at the axilla of each of its leaves, which may be either f wer buds or br-inch buds, according to the age and vigour, or nature of the trre; for there are some trees which produc i ir A wers in buds distinct from those which producę br incl:es, and others that do not. The peach, the cherry, the lilac, and m y other trees and shrubs, may be given as examples of the form r: in these, the flower buds, after fructification has been complsted, die, but do not occasion the death of the branch on which they ítand; and, so anxious has Nature been for the production of branc' es, that it very often happens, in trees of this kind, trat a branch bud is found in the axilla of the fame leaf, with one or two flower buds. Of the latter, many examples may be given ; some of which produce their flowers from the sides of their branches, ex. gr. the Vine and Passion flower : in these, the peduncie only dies ifter the decay of the flower, or ripening of the fruit; but the branch from which they proceed, continues to grow. Orders produce their flowers at the extremity of the young brunch, ex. gr.the Rose: in these, the flower, with its peduncle and part of the extremity of the branch, only decay ; but the under part of the hranch, where completely formed leaves have stood, continues to live, and is capable of producing branches.
The The formation of the leaves, the inhalation and exhalation of plants, the circulation of their fap, the feep of vegetables, their green colour and inclination towards the light, the duration and de cay of the leaves, and the evolution of the flower, successively occu. py his attention. On most of these subjects we find much reason. ing, and not a little hypothesis ; but not so many facts adduced in support of some of his affertions, as we think necessary to produce conviction.
When speaking of the food of plants, (p. 281.) he says,
• The chief food of plants condits of carbon and hydrogen ; the hallow air vefsels carry the oxygen gas, which was formed during the day, out of the plant ; and in the night time, when the rays of the son are wanting to evolve more oxygen gas, they exhale, through the pores of the cutis, carbonic acid gas, which they received from the ground, and which, for want of light, they could not keep fixed.'
This is not enough for one unacquainted with the subje&t ; and one who knows something of it, knows, that there is a difference of opinion concerning the food of plants, and therefore would expect something more than bare assertion. Besides, the subject merits more attention ; for, the knowledge of what constitutes the food of plants, may be useful to the practical agriculturist, as well as the student of botany.
He treats very fully of the impregnation and generation of plants, a subject which merits more attention than is generally paid to it. Many are disposed to doubt the sexes of plants altogether; and few of those who are convinced of its existence, have thought of turning their knowledge of it to account. We are persuaded, many good varieties, both of ornamental and useful vegetables, might be obtained, by impregnating one plant with the farina of another nearly allied to it. Thus, a native vegetable might be impregnated with the farina of a species, the inhabitant of a warmer climate, possessed of superior qualities, and a hybrid be produced, pofTelling some of the properties of its exotic parent, and yet hardy enough to endure a severer climate. Vegetables producing fruit or roots of superior size, but defective in point of flavour, sweetness, or nutritive properties, might be improved by commixture with other varieties or species pofTe fled of these qua lities, but deficient in point of size.
Empedocles and Anaxagoras attributed sexes to vegetables, and Theophrastus takes notice of the difference of fex in the Coryza and some other plants, and says that the fruit of the Palm will not germinate unless the flowers of the male be shaked over the spadix of the female. But the notion which the ancients had of the difference of sex in plants, was by no means accurate. Pliny, in particular, sometimes mistakes the male for the female, and calls
plants male and female, which are hermaphrodite. Sir Thomas Millington was the first who fixed on the stamina as the male organ, and pistillum as the female. From that time the existence or nonexistence of sexes in vegetables, has been a matter of con-' troversy among botanists. To enumerate all the arguments that have been employed by the advocates on both sides, and the exo. periments on which they were founded, would both be tedious and unnecessary ; since the production of vegetable hybrids, by impregnating one fpecies with the farina of another (an experiment which has frequently been repeated), has not only proved the existence of sex in vegetables beyond controversy, but has Thown the particular kind of generation which takes place in them.
M. Willdenow, after taking notice of the principal theories of generation that have been proposed, proceeds to give his opinions of each of them. We shall pass what he says of Equivocal generation, because it has been long exploded.
Of the Animalcular fyftem, he lays (p. 325.),
· The theory of Animalcula in the semen of animals being carried over to the ovarium of the mother, where the new animal is formed, has Leuwenhoeck for its author. Some, therefore, in the vegetable kingdom, allumed preexisting germs or corcles in the pollen, which,: in the mother's ovaries, unfolded themselves into the future plant. A very zealous supporter of this opinion, was Mr Gleichen. Some even went so far as to see, under the microscope, small asses in the semen of an als, and small lime trees in the pollen of a lime. Strange things may be seen, if persons are disposed to see them. Koelreuter's observations, of which immediately, at once overthrow this doctrine. ... The system of preformation, which in former times was much in vogue, is not, even by its most zealous admirers, much in Gited on in the vegetable kingdom. Spallanzani, who, in animale, by means of tedious experiments, attempted to prove the preexistence of the animal before the impregnation of the ovum in the ovaries, fincerely confesses, that there is no preexistence of vegetables like that in animals.
• The Epigenefis, or generation by a commixtion of the fluids given out both by the male and female, is what most physiologists now assume as the only true theory of generation, both in the animal and vegetable kingdom. Koelreuter confirmed it by numerous experiments, of which we shall mention only one. He took of the genus Nicotiana, the Nicotiana rustica and paniculata. The first he deprived of all its stamens, and fecundated its pistil with pollen of the last species. Nicotiana rustica has egg-fiaped leaves, and a short greenish yellow corol; Nicotiana paniculata, a item half as long again as the former, and roundish, cordate leaves, and much longer yellowish green corols. The battard offspring of both, kept in all its parts the middle betwixt the two species. He tried the same with more plants, and the result accorded perfectly with the first. VOL. 11. NO. 21.