56 SURVEY OF THE REPRODUCTIVE PROCESS 



former are antheridia, containing cellules in the usual way, 

 each with an antherozoid in its interior ; but these are not 

 developed for a considerable time after the shedding of the 

 spore. In about the same time the macrospore developes 

 in its interior a prothallial layer, containing archegonia, in 

 one of which the central corpuscule becomes converted into 

 an embryo, the access of the antherozoids for impregnation 

 being effected by the rupture of the spore-coats. In its 

 small dimensions and internal position this prothallial layer 

 presents an evident approximation to a structure presently 

 to be noticed in certain phanerogamic ovules. 



The first development of the impregnated germ is into 

 the cellular suspensor. This grows downwards through the 

 substance of the prothallium into the general cellular con- 

 tents of the spore, and at its farther end the proper embryo 

 is formed. By a change in the direction of growth the 

 latter emerges from the spore, sending upwards a leafy 

 axis, and emitting radicles from below, much in the manner 

 of the embryo of a true seed. The axis increases by lateral 

 pullulations, all assuming a prostrate position, and emitting 

 rootlets as they creep along. Eventually they become inde- 

 pendent phytoids by the decay of the first formed portion 

 of the stem. The fructification is generally in distinct 

 shoots, which assume the form of vertical spikes, with the 

 leaves more closely imbricated, and bearing the sporangia 

 in their axils. 



In the small order of Marsileacese or Rhizocarpere, con- 

 taining a few aquatic plants, the general character of the 

 reproductive process is much the same as in Lycopodiacese. 

 The two kinds of spores are contained in separate capsules 

 within the same multilocular receptacle, termed a sporocarp. 

 The process of germination comes still nearer to that of 

 Phanerogamia than in the case just described, for provision 

 is made for the entrance of the antherozoids, and the exit 

 of the embryonic axis, not by the simple rupture of the 



