Page:An introduction to physiological and systematical botany (1st edition).djvu/219

Rh resinous exudation of Lombardy Poplars, Populus dilatata, Ait. Hort. Kew. v. 3. 406, which he supposes to be the tears of Phaëton's sisters, who were transformed into those trees. Such exudations must be considered as effusions of the peculiar secretions; for it has been observed that Manna may be scraped from the leaves of Fraxinus Ornus, ''Fl. Græc. t.'' 4, as well as procured by incision from its stem. They are often perhaps a sign of unhealthiness in the plant; at least such appears to be the nature of one kind of honeydew, to which the Beech in particular is subject, and which, in consequence of an unfavourable wind, covers its leaves in the form of a sweet exudation, similar in flavour to the liquor obtained from its trunk. So likewise the Hop, according to Linnæus, ''Faun. Suec. 305, is affected with the honey-dew, and its flowers rendered abortive, in consequence of the attacks of the caterpillar of the Ghost Moth, Phalæna Humuli'', upon its roots. In such case the saccharine exudation must decidedly be of a morbid nature.