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their ideas of fimilitude. When Rivinus informs us that enchanter's night-shade has two regular petals, ladies smock four, St. John's wort five, tulip six, and anemony many, every one who knows the part in question, and has learned to distinguish, in dubious cases, betwixt fowers of one peral, and flowers of more petals than one, must enter immediately into the Author's meaning, and be thence enabled to refer each plant to its respective class or division. Let us make a similar experiment in case of figure, and attend the illue. That bind-weed, bell-flower, deadly night-Ahade, and the numerous plants of the mallow and cus cumber tribes, should be made to arrange themselves under a class containing bell-shaped flowers, can appear strange to no one who knows ever so little of the plants that have been mentioned. The resemblance is obvious and striking; and it is next to impoffible that a learner who has been previously instructed in the principles and analysis of Tournefort's method, thould mirtake in making the proper reference to his arrangement. A particular class, he is informed, the Author has allotted for the reception of plants with bell-shaped flowers : gentian, melon, and the plants just enumerated, have manifestly fowers of that description; their place, therefore, in the arrangement, cannot be matter of disquisition or doubt for a moment; it is immediately ascertained. But there are instances in which the determination of the class or primary division, is not a point of such extreme facility. Who, for example, would look for crofswort, ladies bed straw, cleavers, madder, and rhubarb, among the bell-Ihaped flowers ? or expect to find loose-ftrise, pimpernell, speedwell, and borrage conjoined with flowers which in Thape resemble a funnel? Yet these false arrangements, incredible as it may appear, are chargeable upon the method adopted by Tournefort, as are likewise many others of the same kind.'
Our botanist had hitherto supposed the constancy of the rival principles, number and figure, to be equal : he now proceeds, after other observations, to enquire and determine with accuracy, in favour of which distinction to capital a circumftance declares itself. He produces many examples of variations in respect to the first, and then remarks, that in fome of the in. ftances mentioned of occasional variations in point of number, changes little less remarkable or conspicuous are effeéted in the general symmetry and figure of the parts. After this he also mentions some of the most considerable of thote accidental alterations in the figure of the several parts of plants which are totally unconnected with casual variations of number, and unaffected by them.
The result of these disquisitions is given us in the two following, and, as our Author says, evident, consequences : the one, that figure, in general, is not a more infallible distinction than
Pumber. The other, that more frequent variations are exhibited by the petals in point of number, than of figure. On the whole, therefore, we fould have concluded that Tournefort's method of arrangement was preferable to that of Rivinus. But this Writer appears with justice to remark, · Had Tour. nefort, in adopting the figure of the petals for his primary dila tination, preserved it totally unconnected with every other, he would thereby have imparted to his method a degree of excellence absolutely unattainable by that of Rivinus, from the greater inconstancy of its principle or leading character. Far, however, from availing himself as he ought, of lo distinguilhed an advantage, the French botaniit has overlooked it altogether, and, by combining number with figure, and even postponing, the latter to the former, has introduced into his method the inconveniences of either distinction, and thus rendered the execution of his plan more exceptionable than that of his predecellor, and widely different from what would have resulted from a developement of the same principle closely adhered to.'
Dr. Milne acknowledges Tournefort's method to have been justly celebrated, and is particular in illustrating the general scheme, Not only, he says, out of respect to the distinguished character of its author, but because several of the clatics are properly its own, and possess a degree of facility, that could scarce have been expected in a plan of arrangement, which keems to have proposed the investigation of natural families as the standard of excellence. Rivinus made choice of a principle which, being observed with the most scrupulous exactness, had totally excluded every natural assemblage, whether of a primary or secondary kind. It was Tournefort's intention, in adopting a principle that admits of greater latitude, to restore its imagined utility to the science; by re-establishing as far as the artificial character would perinit, those natural clafl:s and genera, which Rivinus, preferring facility to every other advantage, had dismembered and split.'
As figure admits of much greater latitude than number, therefore, our Author obferves, the French botanist's method, however beautiful in the idea, is much more difficult in practice than that of his predeceffor, Rivinus, whose role object was to facilitate the knowledge of the plants. He particularizes the most remarkable of the general distinctions, (in the secondary divisions in Tournefort's method) which are founded principally upon the fruit, as those of the clafles are upon the fower, and he accompanies his account of these distinctions with explanatory observations: he also points out the principal errors, and difficulties attending this schence: for a particular account of all which we must refer the Reader to the work itself, without adding any thing farther relative to what is said upon this celeRev. O&t. 1772.
brated method, than that the Doctor dismisses it by presenting us with a list of the most considerable writers by whom it has been adopted : the list is numerous, but among them all Father Plumier, and Pontedera alone, have ventured to quit the track pointed out by Tournefort.
We now come to an account of methods founded upon the calix or flower cup; of which there are only iwo : the one invented by Peter Magnol, a celebrated professor of botany at Montpelier, and published in 1720, five years after the author's deaththe other delineared by Linnæus, and published in his claffis plantarum, in 738, three years after the publication of the Sexual System : The former, says our Author, is fingular in its kind, and acknowledges principles of diftribution, totally different from any that have hitherto been explained. After a brief view of this particular mode of arrangement, it appears that, facility is by no means its characteristic. "It is in fact, says this Writer, of all others the most difficult in practice, nor do I know that it possesses a single quality, fave novelty alone, to reccminend it. The observations with which it abounds, however ingenious, are frequently whimsical, and calculated to mislead. The very foundation of Magnol's method is deceptive : for, although it fets' out with the calix, and even profesies an uniform adherence to that part of fructification, in characterizing the classes, the learner will not have advanced many fteps, before he finds himself bewildered in diftinctions from the fruit: distinctions least of all to be expected, in a method founded profeffedly on the calix; yet attempted to be made compatible with the principles of fuch method, by the operation of an imagined connection and affinity between the calix and fruit.'
Notwithstanding this censure passed upon the Magnolian method, Dr. Milne allows that there are many circumstances which, under proper restrictions, render the calix no con. temp:ible foundation of a bolanical system. • Of all, or most of these circumstances, he adds, has Linnæus availed himself in the construction of his Method founded upon the calix, which in the idea and execution, is greatly superior to that of Magnol; and is indeed fingularly useful, in familiarizing to the novice in botany, the various appearances of an organ lo important in its pature, and so diversified in form.'
The attention of the Reader is in the next place called to the Sexual E;Jlem, of which the fixth section of this work contains the analysis and examination : it is founded upon the number, proportion, situation and union of the stamina, chives, or flender threads of the power; and proceeds upon a fancied analogy betwixt the several parts of plants and those of animals, suppoling the existence and concourse of the fexes to be as indisputably ascertained in the former as in the latter. The organs indispenfibly necessary to fructification are reduced to two, the stamina and pistils; the necessity of these is evinced by several observations from which it appears, says this Writer,
- That there is no plant capable of furnishing good, wellconditioned seeds, that is not provided with stamina and pistil. That flowers which pofless the highest degree of luxuriance, and have all the stamina metamorphofed into petals, produce no perfect seeds. That seeds equally barren and imperfect, are furnished by such flowers as have their pistil transformed into flender expansions, resembling leaves. That if the ftamina of any plant are cut off before the antheræ or summits have dispersed the powder inclosed within their substance, the fruit is productive of imperfect seeds. That a similar abortion takes place, when, upon the expansion of the flower, the style or ftigma (the summit of the piftil) is cut off ; when the moisture which vers that organ is totally absorbed by continual smoke, or carried off by perpetual showers; when the tops of the ftamina are hindered from opening by sudden frosts, or their powder diluted or washed away by violent rains. These facts prove that the stamina and pistils are absolutely necesary towards the formation of the seeds.
' The seeds of plants, proceeds our botanist, in another place, are true vegetable eggs: as such, they require to be fecundated, before they can be capable of producing a plant similar to the parent-plant. Vegetables then have the necessary organs of the two sexes : but what are these organs and where do they relide?
• It is evident that we must seek for the organs of generation in plants, in the parts where the seeds are formed, where they receive fecundation, and where they take their growth. Those parts are the flower and fruit; which are therefore very properly defined by Linnæus, the organs of generation of plants which serve, the former, for the fecundation of the feeds, the latter for the nourishment of the fætus. Now all plants which bear feeds have stamina and pistils. The stamina are the male parts, the pistils the female. When the stamina and pistils are found collected in the same fructification, as happens in the greater number of plants, the flower is termed hermaphrodite. When the fru&tification contains stamina only, the fiower is termed male, when piltils only, female. Male and female flowers are fumetimes produced upon different parts of the same individual plant, fometimes from different individuals sprung from the same seed. The plants in the former case, are termed androgynous, in the latter, male and female'
In support of this hypothesis of the existence of the foxes in plants, a variety of proofs are offered, some of which are here mentioned; we tall iclcet only that which follows:
« M. Duhamel du Monceau, says our Author, relates an experiment performed by himself and M. Bernard de Julieu, a celebrated French academician, which bids fair to be decisive upon the queftion of the fexes. In the garden of M. de la Serre of the Rue S. Jaques at Paris, was a female turpentine tree, which flowered every year, without furnishing any fruit capable of vegetation. This was a fenfible mortification to the owner, who greatly desired to have the tree increaled. Messrs. Duhamel and Juflicu very properly judged that they might procure him that pleasure with the allistance of a male pistachio tree. They sent him one very much loaded with flowers. It was planted in the garden of M. de la Serre very near the female turpentine tree, which the same year produced a great quantity of fruits, that were well-conditioned and role with facility. The male plant was then removed, the consequence of which was, that the turpentine tree of M. de la Serre in none of the succeeding years bore any fiuit, that, upon examination was found to germinate.
We will here infert some of those arguments which are drawn from the structure, proportion, situation and other circumitances of the sexual organs, and which are thought farther to lupport the doctrine of vegetable fecundation,
"The male duft, we are told, is discharged by its proper organ, at the very time when the ftigma of the pistil is in its greatest vigour, and consequently best disposed to receive the influences of the fecundating matter.-After the discharge of the pollen, or powder of the antheræ (the summits of the chives or itamina) both ftamina and pistils wicher and fall off.— The fiuation of the pillils with respect to the stamina appears favourable for the reception of the fecundating duit. The greater part of aquatic plants flower only above the water, that the fecundation, as Gesner observes, may be performed in air, and the generating substance may not be diluted by the water. Some plants it is remarkable, plunge again into the water, as foon as fecundation is accomplished, and the fruits begin to be formed.–The figure of the pollen in plants of the same species is exa&ly similar; in those of different species and genera, its figure is exceedingly diversified. Hence we may conclude, with fome degree of probability, that the powder in question, being . composition of organized capsules, is not a simple excrement or secretion, as some naturalists have pretended, but a viscus effentially necefiary to plants, and whose function it is to perpetuate the species.'
The doctrine of the sexual difference in plants was not totally unknown to the ancients; they had particularly observed it with regard to palm-trees. Several botanists before the time of Linaus bad distinguished plants into male and female, and