Page:An introduction to physiological and systematical botany (1st edition).djvu/375

 Rh those little animals, chiefly of the Hymenoptera order, and of the genus Cynips, in some vigorous part of the plant, as the leaves, leaf-stalks, young stem or branches, and sometimes the calyx or germen. The parent insect deposits its egg there, which is soon hatched, and in consequence of the perpetual irritation occasioned by the young maggot, feeding on the juices of the plant, the part where it is lodged acquires a morbid degree of luxuriance, frequently swelling to an immoderate size, and assuming the most extraordinary and whimsical shapes. This often happens to the shrubby species of Hawkweed, Hieracium sabaudum, ''Engl. Bot. t. 349, and umbellatum, t.'' 1771, whose stems in consequence swell into oval knots. Several different kinds of Galls are borne by the Oak, as those light spongy bodies, as big as walnuts, vulgarly named Oak apples; a red juicy berry-like excrescence on its leaves; and the very astringent Galls brought from the Levant, for the purposes of dyeing and making ink, which last are produced by a different species of Quercus from either of our own. The common Dog-rose, t. 992, frequently bears large