SPORES AND THALLIDIA. 



15 



The last division of plants wherein the spores are formed deep down in a tissue 

 is that of the Muscinese, which include Mosses and Liverworts. In these plants the 

 spore-producing generation consists of a cellular body, which has arisen from the 

 fruit, is usually seated on a stalk, and in shape is cylindrical, pyriform, or more or 

 less spherical (c/. figs. 191 ^' *■ ^' ^' ^^). We must here remark, by the way, that botanists 

 used formerly to look upon this sporogenous generation of the Moss erroneously 



Fig. 191.— Mosses. 



« Polytrichum commune, the sporogonium to the left concealed by the cap, the sporogonium to the right exposed. 2 xhe same 

 Moes in an earlier stage of development, s Sporogonium of Polytrichum commune with its lid. * The same after the lid 

 has fallen off. ^ Bryum ccBspiticium. e Sporogonium of the same Moss with its cap. ^ The same without the cap, but 

 with the lid still on. 8 The same after removal of the lid, showing the teeth (peristome). 9 A piece of the peristome. 

 10 Antheridia, Archegouia, and Paraphyses of Bryum ctespiticium. n Hylocomium splendcTis. 12 Sporogonium of 

 Hylocomium splendens. ^s AndroBa rupestris with burst sporogonium. 1* Sphagnum cymbifotium, its spherical sporogonia 

 still covered by their lids in the left-hand specimen, is A single sporogonium of the same Moss. 1, 2^ 6^ 11^ 14 natural 

 size ; ', *, «, ?, «, i^, is, is x 5; ', i" X 150. 



as the fruit itself. The only structure rightly to be considered as the Moss-fruit is 

 that in which the embryo is produced as a result of fertilization. If afterwards a 

 new generation springs up from the embryo which has been formed in the interior 

 of the fruit, this generation cannot any longer be described as a fruit even in cases 



