276 REPRODUCTION IN FERNS. 



granules, which the cell produces within it ; and every one of 

 these is capable of itself forming a perfect plant ; as has been 

 ascertained, by cutting the tubes into several pieces. In general, 

 however, all these go to form one young Moss, the cells which 

 they produce uniting together at an early period ; and thus the 

 process is rendered much shorter, than if the whole plant had to 

 be developed from a single cell. 



430. In the Ferns, again, we meet with another form of the 

 same process. The spore- cases are here developed on the backs, 

 or at the edges of the leaves, and differ in form from those of 

 the Mosses ; but the spores which they contain, could not be 

 distinguished from theirs. The thecee or spore-cases are usually 

 nearly globular bodies, attached to the leaf by short stalks, as 

 seen at >, Fig. 79. Although they are singly almost too minute 

 to be distinguished by the unassisted eye, a number of them 

 clustered together form the spots or ridges on the under 



side of the leaves, which are 

 termed sori; these are shown 

 at a. Each theca is sur- 

 rounded by an elastic ring, 

 which has a tendency to 

 straighten itself; and when 

 the spores are mature, the 



theca splits across, and the two halves are separated by the 

 straightening of this ring (as seen at c), so as to allow the spores 

 to escape. If a Fern-leaf, whose fructification has come to 

 maturity (as may be known by the brownish tinge of the yellow 

 or orange spots or ridges on its leaves), be placed with its under- 

 side upon a piece of white paper, this will be found in a day or 

 two covered with a very fine brown dust. These are the spores 

 which are scattered by the bursting of their cases. The process 

 of development of these spores presents several points of interest. 

 In its first stages it closely resembles that of the Marchantia. 

 The outer coat of the spore ruptures, and the inner one projects 

 into a long tube; within which, as well as within the original 

 cavity, new cells are formed from the germs included within it. 

 The first tendency of these newly-formed cells is to grow together, 



