Organography of plants, especially of the archegoniatae and spermaphyta . ungsgeschichte des weiblichen Vorkeimes bei den heterosporeii Lvco-podiaccen, in Botanische Zeitung, liv (1896), p. 160. Adventitious shoots also appear in Lycopodium Phlcgmaria. • See Tart I, p. 49. * Buchtien, Entwicklungsgeschichte des rrothallium von Equisetum, in Bibliotheca Botanica, viii(iS87),p. 24. 214 ASEXUAL PROPAGATION OF THE PROTHALLUS of Lycopodium, and also in many Hymenophyllaceae and Vittariaceae, andthus, as in the Hepaticae, formation of gemmae has arisen frequently andindependently in different series
Organography of plants, especially of the archegoniatae and spermaphyta . ungsgeschichte des weiblichen Vorkeimes bei den heterosporeii Lvco-podiaccen, in Botanische Zeitung, liv (1896), p. 160. Adventitious shoots also appear in Lycopodium Phlcgmaria. • See Tart I, p. 49. * Buchtien, Entwicklungsgeschichte des rrothallium von Equisetum, in Bibliotheca Botanica, viii(iS87),p. 24. 214 ASEXUAL PROPAGATION OF THE PROTHALLUS of Lycopodium, and also in many Hymenophyllaceae and Vittariaceae, andthus, as in the Hepaticae, formation of gemmae has arisen frequently andindependently in different series of the Pteridophyta, as a character ofadaptation. Lycopodium Phlegmaria. Treub found in Lycopodium Phlegmariatwo kinds of gemmae, ordinary ones, and those with thickened outer former are ovoid cell-bodies seated upon a short stalk \ and they growout directly into the new cylindric prothallus. Thick-walled gemmaearise from the prothallus when it finds itself under unfavourable conditionsfor vegetation, and they consist of few cells, each of which has a thick. Fig. 157. Hymenophyllaceae. Formation of gemmae on the prothallus. i, Trichomanes rigidum ; B, gemma ;7. sterigma. From a specimen collected in Venezuela. 2, Hymenophyllum sp.; si, sterigma; wh, primordium ofrhizoid. From a specimen collected in Java. 3, 4,5, Trichomanes venosum ; B, gemma ; .S, sterigma ; F, developingstalk for a gemma. From a specimen collected on the Black Spur Mountains, Australia. 6, Germination of gemma. outer wall. These gemmae are essentially resting buds, and they securethe perennation of the prothallus when the conditions are unfavourable. Hymenophyllaceae. Gemmae are known in the species both of Tricho-manes and Hymenophyllum. I have already carried back the gemmae ofmany Hepaticae to the formation of brood-cells, which frequently developfurther even upon the mother-plant, and this holds also for the gemmae ofthe prothalli of Filicineae. It is sufficient to refer to Fig. 157 in order
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