XI 



LEPTOSPORANGIATJE HETEROSPORE^ 



42s 



IS unusually small in Marsilia, which otherwise resembles 



Pihdaria. 



The phenomena of fecundation are very striking in the 

 Marsiliace^. The mucilaginous layer about the macrospore 

 attracts and retains the spermatozoids, which collect by hun- 

 dreds about it. The mucilage above the archegonium forms 



1. 



2. 



Fig. 250.— Mam/to vestita. Development of the embryo. A, Longitudinal section of 

 archegonium with two-celled embryo; B, similar section of a later stage; C, two 

 transverse sections of a young embryo; D, two longitudinal sections of an older 

 one; I, I, the basal wall; L, cotyledon; st, stem; r, root; F, foot. A-C, XS25; 

 D, X260. 



a deep funnel, which becomes completely filled with the sperma- 

 tozoids. As these die their bodies become much stretched out, 

 so that they look very different from the active ones, with their 

 closely placed coils. The attractive substance here is not con- 

 fined to the material sent out from the open archegonium, as th^ 



