The British species of angiocarpous lichens, elucidated by their sporidia / by W.A. Leighton.

  • Leighton, W. A. (William Allport), 1805-1889.
Date:
1851
Catalogue details

Licence: Public Domain Mark

Credit: The British species of angiocarpous lichens, elucidated by their sporidia / by W.A. Leighton. Source: Wellcome Collection.

    14/196 (page 4)
    ANGIOCARPI, Fries. Apothecium closed, perforated by a pore, or irregularly deWscing; niicleus included, subglobose, ascigerous. In this order of Lichens the apothecium is more or less globose, resting upon or immersed in the thallus, either formed from the thallus itself, or distinct, and consisting of an outer covering or shell {perithecium), varying in colour, black, red, or pale, either entii'ely en- veloping the nucleus, or dimidiate, and situate on the upper or exposed portion. This outer shell or perithecium is (probably in all cases, though not always distinguish- able,) lined v^dth a tunic or membrane, more or less tough and consistent, and either black, brown, or pale and nearly colourless, which completely encloses the nucleus. The nucleus is internally white, or slightly coloured brown, more or less transparent, gelatinous, consisting of hyaline tubes or filaments {asci) of various forms, each ascus con- taining 8 sporidia, varying in shape and size in different species. Intermixed with the asci are generally para- phi/ses, usually considered as abortive asci. When mature, the sporidia escape from the ru])tured asci through the pore or perforation at the apex of the perithecium. Such appears to be the normal condition. In some plants, however, hitherto arranged under the genera of this order, (as Verrucaria niveo-afra, rudis, apJianes, leuco- cepJiala, and others,) there are no asci, the sporidia being innumerable and free, agglutinated into a mass, which dissolves as in many fungi. It may be questionable whether these should be ranked as Lichens correctly, or whether they should be regarded as fungi, cither distinct or parasitic on the crusts of Lichens : but this must be decided by future and more favorable and extended ob- servations.