OF FOREST-TREES. 



141 



Hook, (and other sagacious naturalists,) to shew, that none of these dis- CHAP. VII. 

 eases and infirmities in plants proceed from any pure accidental, but real ""^"V""^ 

 cause ; as flatus, venomous liquor, and infections. Some, even of the 

 minutest animals, are provided with instruments to pierce the very solid 

 substances of trees and plants, and infuse their pestiferous taint ; where 

 likewise they leave their eggs, boring those nestling places with certain 



has three cells, as in the Lilies ; quadruple, when the seed-vessel has four cells, as in the 

 Grass of Parnassus ; there are five stigmata when the seed-vessel has five cells, or five 

 seeds, as in the Geranium, Winter-green, Wood-sorrel ; there are six stigmata when the 

 seed-vessel has six cells, as in the Asarabacca ; there are ten stigmata when the seed-vessel 

 has ten cells, as in the Perk-physic ; there are many stigmata when the seed-vessel has 

 many cells, as may be seen in the Mallows, or in the Poppy, which is furnished with as 

 many receptacles for the seed as there are stigmata. 2. Time. — The stigmata are always 

 in full vigour at the same time with the antherae. For in the Indian Wheat, as Logan ob- 

 serves, on the same day that the antherae burst their inclosure, and hang down in the open 

 air, are seen the bundles and extremities of the styles coming out of the sheath of the spike 

 to open view. 3. Falling off. — The stigmata, in most plants, when they have discharged 

 their office, drop off in the same manner as the antherae do ; which is a most evident sign 

 that the stigmata contribute nothing to the ripening of the fruit, but serve only for the 

 purpose of generation. 4. Being cut off. — If the stigmata be cut off before they have 

 received the impregnating dust of the antherae, the plant is castrated as to the female organs, 

 and the fruit perishes : a sufficient demonstration that the stigma is that part of the 

 female organ of generation destined for conception. The stigma of a flower has, besides, 

 two other singular properties ; namely, that it is always divested of the cuticle or film, 

 nor has it any bark as the other parts, and then it is always bedewed with a moisture. 

 Hence it appears, that the arguments of Pontedera have no force to invalidate this doc- 

 trine. For when he would oppose the doctrine of the generation of plants, the whole 

 force of his argument is drawn from the umbelliferous plants, whose styles are not come 

 up when their stamina appear. But the stigma is that part which serves for the purpose 

 of generation, and not the style, which may be wanting in many, as it is not an essential 

 part of the flower. It is sufficient, therefore, that the stigmata in the umbelliferous plants 

 be in full vigour at the self-same time with the antherae, though the style be lengthened after 

 conception, which is the case also in the Maple. 



The generation, then, of plants is brought about by the antherae shedding their dust on 

 the stigmata. It is not sufficiently clear in what way the generation of animals is accom- 

 plished ; but thus far we are certain, that the male sperm must come in* contact with the 

 female organ, if there be any impregnation. In the vegetable kingdom the genital dust 

 is carried by the air to the moist stigmata, where the particles burst and discharge their 

 exceedingly fine or subtle contents, which impregnate the ovary. That this is the case, 

 will be shewn by the following arguments. 1. Sight. — When a plant is in flower, and the 

 dust of the antherae is flying about, part of this dust lights upon, and is seen to cling to the 

 stigma. The flower of the Pansies shews this in a most agreeable manner; for, when the 

 Volume 11. T 



