LIFE HISTORY OF A MOSS 
205 
bearing cells. Thus photosynthesis may be carried on, 
though of course to a very limited degree. The sporo- 
phyte of the true mosses seems to occupy an intermediate 
position between those of Sphagnum and the fern, and, as 
we ascend from the lower form in Sphagnum to the higher 
form in the fern, the transition is largely characterized by a 
decrease in the amount of fertile tissue and an increase in 
the relative amount of sterile tissue of the sporophytes. 
FIG. 148. Protonemata of a moss bearing young gametophyte buds. 
190. Vegetative Multiplication. Extensive experiments 
seem to indicate that every living cell of a moss-plant can 
develop protonemata or in other words is a potential 
spore. These protonemata like those produced by the 
germination of spores, produce buds which may develop 
into mature plants. The production of entire plants or 
of parts of plants in this way, by portions of the vegetative 
body, is called regeneration. In some species of mosses the 
