Organography of plants, especially of the archegoniatae and spermaphyta . - of the Polypodia-ceae does not always develop in the same manner. In germination thecell-filament is first formed from the spore. Its length depends upon See p. 214. 202 CONFIGURATION OF THE PROTHALIUS OF PTERIDOPHYTA. Fig. 148. Acrostichum peltatum. Sporangium inwhich spores have germinated while it was still attachedto the sporophyte. The spores have formed only cell-rows. MasniCed. able conditions of illumination, external factors. I have already pointed out when speaking of the Hepa-ticae that the form of the germ-
Organography of plants, especially of the archegoniatae and spermaphyta . - of the Polypodia-ceae does not always develop in the same manner. In germination thecell-filament is first formed from the spore. Its length depends upon See p. 214. 202 CONFIGURATION OF THE PROTHALIUS OF PTERIDOPHYTA. Fig. 148. Acrostichum peltatum. Sporangium inwhich spores have germinated while it was still attachedto the sporophyte. The spores have formed only cell-rows. MasniCed. able conditions of illumination, external factors. I have already pointed out when speaking of the Hepa-ticae that the form of the germ-plant depends upon external conditions^ and that the filamentous form is alwaysable to arrive at favourable condi-tions of illumination, in the sameway as these are attained to oftenby the seedlings of Spermophytathrough the elongation of the hypo-cotyl. Now in the Polypodiaceaethis filamentous stage is not, or onlyrarely, missed out even in the mostfavourable conditions ^. If the sporesgerminate closely together this stagepersists longer (Fig. 150, F),and notinfrequentlya branching ofthe threadmay take place; where the sporesgerminate isolated in most favour-surface-growth may begin in the secondcell of the thread-. Ifound this to be thecase in all the germ-plants of Pteris longi-foli
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