. The structure and development of mosses and ferns (Archegoniatae). -gated by Bower (6). He found that there were two types of Fig. 172.—Pinna from the leaf of Cys- ^ J , topteris bulbifera, with a bud ik) apOSpOry, as he named the ^t the base, X2; s. the sori (after phenomenon, one where the pro- Atkinson).thallium was produced from a sporangium arrested in its normal growth, and by active multi-plication of the cells of the stalk and capsule w^all forming aflattened structure, which soon showed all the characters of anormal prothallium with sexual organs. In the second case theprothallia gr
. The structure and development of mosses and ferns (Archegoniatae). -gated by Bower (6). He found that there were two types of Fig. 172.—Pinna from the leaf of Cys- ^ J , topteris bulbifera, with a bud ik) apOSpOry, as he named the ^t the base, X2; s. the sori (after phenomenon, one where the pro- Atkinson).thallium was produced from a sporangium arrested in its normal growth, and by active multi-plication of the cells of the stalk and capsule w^all forming aflattened structure, which soon showed all the characters of anormal prothallium with sexual organs. In the second case theprothallia grew out directly from the tips of the pinnae, andthere was no trace of sporangia being formed previously. Thefirst observations of these phenomena w^ere made upon twovarieties, Athyrhim iilix-focmina var. clarissima and Poly-stichum angulare var. pulcherrinmm, but since, Farlow^ (2) hasdiscovered the same phenomenon in Pteris aquilina. In thelatter the prothallia were always transformed sporangia. Thephenomenon of apospory was first observed by Druery (i, 2). 310 MOSSES AND FERNS chap. The production of secondary sporophytes as adventitiousbuds upon the sporophyte is a regular occurrence in somespecies. Asplenium hiilhiferum and Cystopteris bulbifera arefamihar examples of such sporophytic budding. In these largenumbers of buds are formed which soon develop all the charac-ters of the perfect sporophyte. Very early a definite apical cell isestablished from which all the other parts are derived. InCamptosorus rhizophyllus, the walking fern of the EasternUnited States, a single bud is formed at the tip of the slenderleaf which bends over until it takes root. From this terminalbud another leaf grows and roots in the same way. Classification of the Leptosporangiatce The Leptosporangiatse fall into two groups, which may betermed orders, although the two families in the second order(Hydropterides) are not closely related to each other, but eachhas nearer affinities with certain
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