. Biology . hardened the capsule a single germ ceU, the archesporium, di-vides six consecutive times, forming 64 spores, each spore beingenclosed in a firm covering (shell or epispore. Fig. 49,1). Whenripe, the sporangium bursts open by contraction of the cellsof the annulus, and the spores are scattered from the leaves tothe ground. The Sexual Generation (Gametophyte).—After some months onthe ground the spores absorb moisture, the epispore burstsopen, and the spore cell or endospore begins to swell and to Fig. 50.—Germination of the spore and formation of the prothallium. A,Young
. Biology . hardened the capsule a single germ ceU, the archesporium, di-vides six consecutive times, forming 64 spores, each spore beingenclosed in a firm covering (shell or epispore. Fig. 49,1). Whenripe, the sporangium bursts open by contraction of the cellsof the annulus, and the spores are scattered from the leaves tothe ground. The Sexual Generation (Gametophyte).—After some months onthe ground the spores absorb moisture, the epispore burstsopen, and the spore cell or endospore begins to swell and to Fig. 50.—Germination of the spore and formation of the prothallium. A,Young plant leaving the spore case; B, similar stage after one cell division hasoccurred {p, protenema; s, spore case; r, root). Later stages in formation of theyoung prothallium are shown on the left, and below a fully developed prothalliumwith archegonia and antheridia. In the notch above is a figure (life size) of thesame prothallium. (From Sedgwick and Wilson after Suminski.) REPRODUCTION OF THE FERN 125.
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Keywords: ., bookcentury1900, bookdecade1910, bookpublishe, booksubjectbiology
