120 MOSSES AND LIVERWORTS 



between the mosses and the liverworts, for in 

 the Bog-mosses (Sphagna) the earliest sign of 

 life does not take the form of the green thread, 

 which in most mosses develops from the spore, 

 but is represented by a small flat plate or frond, 

 closely resembling that which, as just mentioned, 

 is formed from the spores of many liverworts. 

 I may here refer to a curious feature which occurs 

 in young plants of that small family of mosses 

 to which the beautiful Pellucid Pour-tooth Moss 

 (Tetraphis pellucida), already alluded to more 

 than once, belongs, and which may possibly have 

 some bearing on the present subject. In these 

 plants the earliest leaves are quite different in 

 form from those which subsequently clothe the 

 stem, and have a considerable resemblance to 

 one of the frondose liverworts, as will be seen 

 by a reference to Plate VI. fig. 19, which repre- 

 sents three which were taken from a plant of 

 the last-named moss. I have often wondered 

 whether these germ-leaves which, by the way, 

 soon disappear, and are never repeated in the 

 subsequent life of the plant may form another 

 link, as regards outside form at least, with the far- 

 off past, when the two tribes were more intimately 

 connected than they are at the present day. 



The subject of the gradual development of the 

 fully formed plant from these very early be- 

 ginnings is far too abstruse and difficult to be 

 dealt with in an elementary work such as the 



