INTRODUCTION. xv 



experiment : I removed a portion of the surface from the pots 

 in which I had Mosses growing from seeds, and I found, (pro- 

 vided I did not go deeper than the conferva-like substance had 

 penetrated,) that the green part of the conferva, and ultimately 

 the Moss itself, was reproduced. And I have since found, that 

 the small creeping roots of Polytrichum commune, and other 

 Mosses, when the soil in which they grow is exposed to the air, 

 throw out green articulated filaments, and produce young plants 

 in a much shorter time than what it takes to produce them from 

 seed. I find the time which Mosses remain in the conferva state, 

 before they produce their true leaves, to vary considerably in 

 different species, and even in the same species under different 

 circumstances. When regularly supplied with moisture, Funaria 

 hygrometrica, Gymnostomum pyriforme, Didymodon purpureum, 

 Bryum hornum, and some others, produce their true leaves in 

 about three weeks from the time of sowing ; Polytrichum undu- 

 latum requires two months ; and Polytrichum aloides sometimes 

 continues four months in the conferva state ; the last mentioned 

 in that state is the well known JByssus velutina, an excellent 

 drawing of which is given in Dillwyn's British Conferva, PI. 77. 



" The duration of the green part of the conferva-like filaments 

 on the surface, after the Mosses produce their true leaves, depends 

 much on the soil and situation in which they grow ; in Phascum 

 serratum, and Polytrichum aloides, they are almost always present ; 

 and in some Mosses, supposed to be annual, I have found them 

 remain and throw up plants in succession for several years." 



The seeds, or sporules of Mosses differ, in toto, from the seeds 

 of the more perfect orders of plants ; those, for example, of the 

 Monocotyledonous and Dicotyledonous plants. They have no 

 integument, no embryo, consequently no radicle and plumule. 

 The sporule is, in itself, an homogeneous substance, producing 

 indifferently from its surface, roots and stems. Indeed, Dr. Th. 

 Fr. Ludw. Nees Von Esenbeck, in a valuable paper " on the ger- 



