. Comparative morphology and biology of the fungi, mycetozoa and bacteria . Plant morphology; Fungi; Myxomycetes; Bacteriology. CHAPTER III.—SPORES OF FUNGI. 93 Section XXV. In most Lichen-fungi with open hymenia the mechanism for the ejection of the spores is similar to that which has now been described, though it differs from it in particular points which appear to me to require further investigation. The structure of the hymenia is essentially the same as in the Discomycetes; there is, according to Tulasne, the same turgescence of the mature ascuii in both, and the same simultaneous ejectio
. Comparative morphology and biology of the fungi, mycetozoa and bacteria . Plant morphology; Fungi; Myxomycetes; Bacteriology. CHAPTER III.—SPORES OF FUNGI. 93 Section XXV. In most Lichen-fungi with open hymenia the mechanism for the ejection of the spores is similar to that which has now been described, though it differs from it in particular points which appear to me to require further investigation. The structure of the hymenia is essentially the same as in the Discomycetes; there is, according to Tulasne, the same turgescence of the mature ascuii in both, and the same simultaneous ejection through one or more longitudinal fissures in its apex* The asci are emptied one after another as they ripen, and the spores, according to Tulasne, are flung outwards to a distance of about one centimetre; the sudden discharge of many asci at once has not been observed. The differences alluded to above are, that the apices of the asci do not project above the surface of the hymenium but continue on a level with it or a little beneath it, and that the pressure on the asci from without appears to be a chief cause of the bursting of the asci and of the ejection of the spores. The ejection of the spores is in fact due to the action of water, which causes a con- siderable swelling throughout the gelatinous hymenium in the direction of its surface, and consequently a lateral pressure on its turges- cent asci. The pressure is moreover increased by the resistance which is offered to the superficial enlargement of the hymenium by the thallus which bears it, and which has less capacity for swelling by absorption of water, or by special thallus-margins or excipula circumscribing the hymenium, which, as Tulasne has shown, bend in such a manner when they absorb water, that they directly oppose the enlargement of the surface of the hymenium. Ejection of spores from an ascus withdrawn by isolation from the influence of these pressures, such as easily occurs in other Discomycetes, has never
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