In the Thallophytes the cytoplasm may be segmented by constriction, due to the in-growth of a new cell wall from the old one, as in Spirogyra and Cladophora, or by the formation of cleavage furrows in which the new cell-wall is secreted, as occurs in the formation of the spores in many Algae and Fungi.
By means of the calamistrum the silk secreted by the cribellum is teased into a fine thread which is twisted round the main threads of the web, giving it a very characteristic woolly or flocculent appearance.
The exciting cause of the hypertrophy, in the case of the typical galls, appears to be a minute quantity of some irritating fluid, or virus, secreted by the female insect, and deposited with her egg in the puncture made by her ovipositor in the cortical or foliaceous parts of plants.
The book, a caustic arraignment of the course taken in connexion with the annexation of Texas and the war with Mexico, made a strong impression, and the political philosophy secreted in its lines became a part of household literature.
Civets are characterized by the possession of a deep pouch in the neighbourhood of the genital organs, into which the substance known as civet is poured from the glands by which it is secreted.
