Text-book of botany, morphological and physiological . s among the Hymenomycetes; and in many cases an alternation of generationshas already been recognised, in so far as the receptacles in which the ascospores areproduced owe their origin to a conjugation or sexual union which takes place on themycelium (as in Erysiphe, Peziza, Ascobolus, Eurotium, &c.). Want of space compelsme to limit my special descriptions to examples of only a few families of the order. (i) The simplest forms of the Ascomycetes are the Yeast-fungi or Ferments of thegenus Saccharorayces\ which cause the alcohohc fermentat
Text-book of botany, morphological and physiological . s among the Hymenomycetes; and in many cases an alternation of generationshas already been recognised, in so far as the receptacles in which the ascospores areproduced owe their origin to a conjugation or sexual union which takes place on themycelium (as in Erysiphe, Peziza, Ascobolus, Eurotium, &c.). Want of space compelsme to limit my special descriptions to examples of only a few families of the order. (i) The simplest forms of the Ascomycetes are the Yeast-fungi or Ferments of thegenus Saccharorayces\ which cause the alcohohc fermentation of the saccharine juicesof plants (must, cider, &c.), of beer or of artificial solutions which contain sugar inaddition to nitrogenous substances (albuminoids or ammonia-compounds) and mineralsubstances which form the food of plants. These Fungi consist of small roundishor ellipsoidal cells, which grow in fluids, and, in nourishing themselves, cause their de-composition, with formation of alcohol, carbonic acid, and other substances. Each. ^ Max Rees, Botan. Unters. iiber die Alkoholgahrungspilze. Leipzig 1870. [Compare alsoHuxley on Yeast, Contemp. Rev. Dec. 1871 ; Pasteur, New Contributions to the Theory of Fer-mentation, Comptes Rendus, 1872, pp. 784-790, and Quart. Journ. Micr. Sc. 1873, p. 351.] FUNGI. ^55 yeast-cell produces similar new cells by the protrusion of small projections at first re-sembling warts, which soon attain the form and size of their mother-cell, and sooner orlater become detached from the narrow points of union. Usually they remain for atime united, and thus form combinations of shoots which may perhaps be considered asbranched hyphae with short, roundish, easily detached segments. When the supply ofnourishment is less abundant,—for instance, when the yeast is grown on cut slices ofpotato, turnip, Jerusalem artichoke, or carrot, the yeast-cells grow to a more considerablesize, their protoplasmic contents produce, by free-cell-formation, from i to
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