THE HIGHER CRYPTOGAMIA. 101 



and starch-granules appear in their interior (PL XIV, 

 fig. 19 b). They change no further until maturity. This 

 double nature of the cells of the interior of the capsule 

 brings to mind the development of the elaters of the 

 Targionieae and Marchantieae. The young conditions of 

 the elaters of the latter answer exactly to the permanent 

 state of those cells of Riella which are intermixed with 

 the spores and contain starch-granules. Piella thus, in 

 more than one point, forms an intermediate link between 

 the Riccieae on the one hand, and the Targionieae and 

 Marchantieae on the other. 



