PTERIDOPHYTA 



145 



In Selaginella (Fig. 38), while the embryo closely 

 resembles that of Lycopodium, the gametophyte is very 

 different. The sporophyte produces two sorts of spores, 

 large and small. The former, the macrospores, produce 

 a rudimentary gametophyte, which bears only archegonia 

 (Fig. 38, E). The gametophyte projects from the spore 

 but little, and until its later stages is contained entirely 

 within the macrospore. In germination there are first 



cot x 9/eJ- em 



FIG. 38 (Lyeopodinere). A, a branch of one of the smaller club-mosses 

 (Selaginella) with t\v sporangial spikes, sp ; B, longitudinal section of 

 spike showing a single macrosporangium, wa,and several microsporan- 

 gia, mi : C, germinated microspore containing the rudimentary male 

 gametophyte; r, the single vegetative cell; an, the antheridium; D, a 

 spermatozoid (after Belajeff) ; E, germinating macrospore with the 

 female gametophyte protruding; ar, archegonia; F, a single arche- 

 gonium ; G, a young embryo, em, attached to the suspensor, sus, whose 

 base remains within the archegonium ; H, young sporophyte, still at- 

 tached to the gametophyte within the macrospore; cot, cotyledons; 

 r, root. 



produced within the spore numerous free nuclei, be- 

 tween which, later, cell-walls arise, forming a continuous 

 tissue much as in the " embryo-sac " of the flowering 

 plants. The formation of the gametophyte begins in 

 Selaginella before the spores are set free from the 

 sporangium. The small spores or microspores produce 

 an even more rudimentary gametophyte (C), which is 



