36 MOSSES AND FERNS CHAP. 



ing of the exospore, which also shows a distinct striation, the 

 outer layer being much thicker and denser than the inner ones. 

 The nucleus of the ripe spore is remarkably small, and it is 

 evident that the dense contents of the ripe spore are largely oil 

 or some similar soluble substance, as in microtome sections 

 there is very little granular matter visible. 



At the same time that the first division wall forms in the 

 embryo, the outer cells of the venter begin to divide by 

 periclinal walls, so that the single layer of cells in the wall of 

 the unfertilised archegonium becomes changed into two, and 

 the basal portion becomes still thicker ; the neck takes no part 

 in this later growth. The cells of the venter develop a great 

 deal of chlorophyll, which is quite absent from the sporogonium 

 itself, and before the spores are ripe the inner layer of cells of 

 the calyptra (venter) becomes almost entirely absorbed, so that 

 only traces of these cells are visible when the spores are ripe. 

 The w r all of the sporogonium also disappears almost completely 

 as the latter matures, but usually in microtome sections traces 

 of this can be made out in the ripe capsule, although the cells 

 are very much compressed and partially disorganised. The 

 contents of these cells, as well as the inner calyptra cells, no 

 doubt are used up to supply the growing spores with nourish- 

 ment. Thus, when ripe, the spores practically lie free in the 

 cavity surrounded only by the outer layer of calyptra cells. 

 The neck of the archegonium persists and is made conspicuous 

 by. the dark brown colour of the inner walls of the cells. 



Hitherto the germination of the Ricciaceae was only known 

 in R. glauca (Fellner (i) ). The account here given is based 

 upon observations made upon R. trichocarpa a very common 

 Californian species. It fruits in winter and early spring, and 

 the spores remain dormant during the dry summer months. 

 If the spores are sown in the autumn they germinate within a 

 few days by bursting the massive black exospore, through 

 which the colourless endospore enclosing the spore contents 

 projects in the form of a blunt papilla. This rapidly grows 

 out into a long club-shaped filament (Fig. 8, A), much less in 

 diameter than the spore, and into this the spore contents pass. 

 These now contain albuminous granules and great numbers of 

 oil-globules, and some chlorophyll bodies, which at first are 

 small and not very numerous. They, however, increase rapidly 

 in size, and divide also, so that before the first cell division 



