. A handbook of cryptogamic botany. Cryptogams. 86 VASCULAR CRYPTOGAMS Order 4.—Hymenophyllace^. The oophyte generation is known but in a very few species of HymenophyllaceEe, Where it has been observed (some species of Hymenophyllum and Trichomanes) it differs from that of other ferns, and is usually filiform, closely resembling the protoneme of a moss, but somewhat coarser. Antherids appear to be produced aX the middle of these filaments, and archegones at their extremity. But apogamy is much more common in the Hymenophyllaceae than in any other family of ferns, and it is doubtful whether it
. A handbook of cryptogamic botany. Cryptogams. 86 VASCULAR CRYPTOGAMS Order 4.—Hymenophyllace^. The oophyte generation is known but in a very few species of HymenophyllaceEe, Where it has been observed (some species of Hymenophyllum and Trichomanes) it differs from that of other ferns, and is usually filiform, closely resembling the protoneme of a moss, but somewhat coarser. Antherids appear to be produced aX the middle of these filaments, and archegones at their extremity. But apogamy is much more common in the Hymenophyllaceae than in any other family of ferns, and it is doubtful whether it does not even occur regularly in some species. Bulbils or gemmae are produced abundantly on the pro- thallium, consisting of a small number of cells, and borne on pedicels or sterigmas. They germinate with extreme slowness. In Trichomanes pyxidiferum (L.) the prothallium is ar^ -;:s=^st£p^ frequently an aposporous growth, derived from imperfect arrested sporanges, or even from cells of the placenta. The archegones are borne on peculiar structures, known as archegoniophores^ mas- sive outgrowths of the prothal- lium, each archegoniophore bear- ing either a single archegone or several. The archegoniophore is usually a multicellular structure. Fig. 61.—Archegoniophore of Trichomanes pyxi- and the VentCrS of the archegOnCS di/erum L., bearing five archegones, ar. of .,-,,.. rr^ different ages (x 175). (After Bower.) are imbedded in Its tissue. T. alatum (Sw.) is habitually apo- gamous, and is possibly never reproduced sexually. Aposporous pro- thallia spring in great numbers from all parts of the frond, often quite independent of the sori, and are more flattened and ribbon-Uke in struc- ture than those of most Hymenophyllacese. They produce large numbers of stalked gemmae. Archegones have never been observed in this species, and the antherids are imperfect, and apparently functionless The spores are multicellular before germination. The archegones differ from those of other f
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