314 



PHY 



THE UNIVERSAL HERBAL; 



P H'Y 



formation of Fungi, merely by the fermentation of putrefying 

 vegetable matter : their sudden rise, and the places which 

 some of them always occupy, led them to form this idea. 

 Though Patrin, and some later philosophers, suppose, that 

 the last members of the organized body may, like the species 

 of Boletus, and the intestinal worms, have their origin from 

 generatio aquivoca; I must confess that their hypothesis, 

 notwithstanding its ingenuity, never appeared to me sufficiently 

 plain. 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 

 in the vegetable kingdom, assumed pre-existing germs or 

 corcles in the pollen, which in the mother's ovaries formed 

 the future plant. The most 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 ass, and small 

 lime-trees in the pollen of a lime. Strange things may be 

 seen, if persons are disposed to see them. Koelreuter's obser- 

 vations at once overthrow this doctrine. The system of 

 pre-formation, which in former times was generally admitted, 

 is now, even by its most zealous admirers, much doubted in 

 the vegetable kingdom. Spallanzani, who in animals, by 

 means of tedious experiments, attempted to prove the pre- 

 existence of the animal before the impregnation of the ovum 

 in the ovaries, freely confesses, that there is no pre-existence 

 of plants like that in animals. The Epigenesis, or generation 

 by a commixture of the fluids given out both by male and 

 female, is what most physiologists now assume as the only 

 true theory of generation both in the animal and vegetable 

 kingdoms. Koelreuter confirmed it by numerous experiments, 

 of which we shall mention one only : He planted the Nico- 

 tiana rustica and paniculata. The first he deprived of all its 

 stamens, and fecundated its pistil with pollen of the last spe- 

 cies. Nicotiana rustica has egg-shaped leaves, and a short 

 greenish yellow corol ; Nicotiana paniculata, a stem half 

 as long again as the former, and roundish cordate leaves, and 

 much longer yellowish green corols. The bastard offspring 

 of both, kept in all its parts the middle betwixt the two spe- 

 cies. He tried the same with more plants, and the result 

 accorded perfectly with the first. Were we therefore to admit 

 the animalcula seminalia, the hybrids could necessarily not 

 have differed in their form from the male plant; and, on the 

 other hand, were the system of evolution founded in nature, 

 they would have the same form as the female plant. The 

 hybrid, however, was intermediate between both ; it therefore 

 certainly adopted some parts both from father and mother, 

 and was formed by Epigenesis. Koelreuter could only obtain 

 hybrids by intermixing similar plants. Dissimilar plants never 

 produced them, even though, according to our system, they 

 belonged to one genus. It appears by this, that nature seeks 

 to avoid unnatural mixtures. The instance of mules not 

 generating, as it was once believed at least, induced many 

 philosophers to make it an axiom, that hybrids are barren. 

 But we now know a good many instances in zoology of 

 hybrids being very productive; and even the instance of mules 

 does not prove any thing, as in warm climates they are some- 

 times prolific. Koelreuter likewise found hybrids of various 

 species of tobacco, and some more plants, to be sterile, the 

 pistil in them being perfect, but the stamens not completely 

 formed. But there are now several instances of hybrid plants 

 which retain their original form, and propagate themselves. 

 F shall mention a few, with their parents. Sorbus hybrida : 

 the mother was Sorbus aucuparia; the father, Crataegus 

 aria. Rhamnus hybridus : the mother was Rhamnus al- 

 pinus ; the fath'.i, Rhamnus alaternus. What mixtures do 

 not the species of Pelargonium produce in our gardens? All 



plants of the 21st, 22d, and 23d classes of Linneus, mostly 

 generate prolific hybrids. Linneus wrote a particular treatise 

 on hybrids, in which he attempted to explain the origin of 

 some particular plants ; but unfortunately he has given nothing 

 but conjectures, for none of his observations accord with 

 experience. Should it not, from the observations made with 

 regard to the hybrids of the animal and vegetable would, be 

 laid down as a rule, with some exceptions, that all hybrids 

 are productive, but that some only want a warm climate to 

 unfold the male semen ? I do not attempt to establish this 

 rule as a certain truth; I rather wish,- that philosophers 

 would consider this subject more accurately, and attend more 

 to the hybrids of different climates, in order to discover the 

 truth. But Koelreuter made some experiments, which afford 

 the clearest proof of the doctrine of Epigenesis, and the 

 fructification of plants. I shall only mention one of his obser- 

 vations as an instance. He obtained a hybrid from Nico- 

 tiana rustica and paniculata. Nicotiana rustica was the female 

 plant, paniculata the male. The hybrid, like all the others 

 which he brought up, had imperfect stamens, and kept the 

 medium between the two species. He afterwards impregnated 

 this hybrid with Nicotiana paniculata, and got plants which 

 much more resembled the last. This he continued through 

 several generations, till in this way, by due perseverance, he 

 actually changed the Nicotiana rustica into the Nicotiana 

 paniculata. By these and other experiments, often repeated, 

 and made in various ways and upon other plants, it is quite 

 obvious, that there is no pre-formation in plants. According 

 to the theory of Epigenesis then, the fluids of the male and 

 female are mixed, and an offspring is obtained from these two, 

 which in form and properties resembles both father and 

 mother. It were to be wished that all theories could be 

 proved in as convincing a manner, as generation can be 

 demonstrated by the number of discoveries on this head, 

 made in the animal and vegetable kingdom. 



" But there have been philosophers, both in former and 

 modern times, who in plants have altogether denied the 

 existence of sexes. Smellie seems to favour this opinion, as 

 he repeated an experiment of Spallanzani's, with a female 

 plant of hemp, which he kept remote from all male plants, 

 and notwithstanding obtained, though in a small quantity, 

 perfect seeds, and hence he deduces his argument. But such 

 experiments are too difficult to be free from error; and who 

 can positively assert, that he has not, even with the greatest 

 attention, been deceived? Spallanzani placed his female plant 

 in a room, to which no insects could get, and, for the greater 

 security, likewise covered it. But could he, before the first 

 flower appeared, distinctly enough distinguish the female 

 plant of the hemp? And could not a very small minute insect 

 escape his eyes, and effect a fecundation? Besides, how often 

 do we find on hermaphrodite plants a single stamen ; which 

 perhaps was here the case ? The few seeds which he got, 

 prove, that a few single. parts were necessarily fecundated. 

 But even supposing that in hemp the female plant produces 

 ripe seeds without fecundation, can we apply any conclusion, 

 however just from this single plant, to every other vegetable. 

 We have in the animal kingdom an instance in the Aphis, 

 an insect which, without the aid of a male, propagates itself 

 till autumn. But who would, from this isolated observation, 

 founded as it is in truth, attempt to deny in all animals the 

 existence of a difference of sex ? Since Gleditsch first, in a 

 botanic garden, impregnated the Chamserops humilis, which 

 is a female plant, with pollen of the male plant, whicn Koel- 

 reuter sent to him from Karlsruhe, and obtained ripe seeds 

 and young plants, which before never had been possible, 

 thousands of similar experiments have been made, which pu 



