Organography of plants, especially of the archegoniatae and spermaphyta . eroof does so as well. This is alsothe case in the germ-plants of Mar-chantia polymorpha, but subsequent-ly confervoid septate cell-threadssprout from the bottom, sometimesalso from the sides and roof, of thechamber; the same features are foundin Boschia, Preissia, Lunularia, Fe-gatella, Targionia; on the other handin Reboulia, Grimaldia. Fimbriaria,Duvalia, and some species of Plagio-chasma, the whole of the tissue be-neath the upper surface of the thallusexhibits an apparently irregularnet-work of small and large air-c
Organography of plants, especially of the archegoniatae and spermaphyta . eroof does so as well. This is alsothe case in the germ-plants of Mar-chantia polymorpha, but subsequent-ly confervoid septate cell-threadssprout from the bottom, sometimesalso from the sides and roof, of thechamber; the same features are foundin Boschia, Preissia, Lunularia, Fe-gatella, Targionia; on the other handin Reboulia, Grimaldia. Fimbriaria,Duvalia, and some species of Plagio-chasma, the whole of the tissue be-neath the upper surface of the thallusexhibits an apparently irregularnet-work of small and large air-chambers communicating with one construction is brought about by the development of cell-plates from thewalls and roofs of the air-chambers, and these project into the chambersand so divide them incompletely by septa. The narrower the communi-cation between the several chambers and the breathing-pores the slowerwill be the transpiration. The several different conditions of life to whichthese forms are adapted have not, however, been thoroughly Fig. 67. Exormotheca Holstii. Upper figure : por-tion of a thallus seen from the upper side. Lowerfigure; thallus in vertical section. The assimilation-tissue is indicated by shading. Lower less highly mag-nified than the upper figure. tion of the transpiration may, however, be of use to the antheridia which require water for thecHscharj^e of the sperniatozoids. See also Solms-Laubach, tJber Exormotheca, Mitten, eine wenig bekannte Marchantiaccen-gattung, in Botanische Zeitung, Ixiv (1S97), P- • See Kamerling, Zur Biologie und Physiologie der Marchantiaccen, in Flora, Ixxxiv ^Erganzungs-band zum Jahrgang 1S97 . 76 VEGETATIVE ADAPTATION IN HEPATICAE Water-tissue. It is of less interest to us that in many Marchantieaeand Riccieae, which possess a thick thallus, a storage-tissue lies under theassimilation-tissue, and in it water especially can be stored. The formationof mucilage may also be regarded as serving th
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