I know it still galls you that he was willing to help pay for your college education, but not Katie's.
Various local hypertrophies, including galls, result from the increased growth of young tissues irritated by the punctures of insects, or by the presence of eggs or larvae left behind.
Irritation and hypertrophy of cells are common signs of the presence of parasites, as ovinced by the numerous malformations, galls, witches-brooms, &c., on diseased plants.
Phytophthora in potatoes., If, on the other hand, the irritating agent is local in its action, causing only a few cells to react, we have the various pimples, excrescences, outgrowths, &c., exhibited in such cases as Ustilago Maydis on the maize, various galls, witchesbrooms, &c.
Excrescences may be divided into those occurring on herbaceous tissues, of which Galls are well-known examples, and those found on the woody stem, branches, &c., and themselves eventually woody, of which Burrs of various kinds afford common illustrations.
