CliYI'TOGAMS 



209 



ihi ni iciospi 10 

 AMtli iiiotlnlhuni 

 (p) bearing ar- 

 chegonia at tlie 

 time of fertiliza- 

 tion. 



— Oampbkli,. 



of Selaginella spores. In the microspore these cells, 



filling the wliole interior, compose an antheridium, with 



only the slightest rudiment of a protliallium ; and 



within this aiitlieridial body are formed antherozoids. 



In the macrospore a reduced prothallium appears. This 



linally increases sufficiently to burst 



open the spore at one end (Fig. 356); 



and on the exposed surface several 



archegonia develop. Fertilization 



takes place after the spores have 



fallen to the ground, wlien water is 



present to allow the antherozoids to 



make their way to the archegonia. 



Then, as in Ferns, an embryonic plant 



is formed, which soon develops stem, 



root, and leaves. 



487. Two points are to lie particu- 

 larly noted with regard to the repro- 

 duction of Selaginella : 



(1) Spores are fif two kinds as regards (a) oiigin, (i) size, 

 (c) ultimate development. For the}' tiriginatc in different 

 kinds of sporangia, are very unequal in size, and give 

 rise to antlieridia and arcliegonia, respectively. This con- 

 dition is foreshadowed in the Ferns, of whicli some species 

 have two sorts of prothallia (§ 480). Mere (in Selaginella) 

 the differentiation extends to the spores and sporangia,. 



(2) The gametophyte (prothallial structure) is rcduceil 

 so much that it is held in tlie original spore walls, and has 

 lost all independence, possessing neither chlorophyll nor 

 rliizoids. 



488. Other Pteridophytes whicli one will frccpiently 

 see are Lycopodiiuii, tlie tUub Moss, and Equisetum, the 

 Scf>uring Rush or lldrsetail. 



489. Lycopodium ( Fig. -loT), to be met A\'it]i in woods 

 and old f)astures and in partly shaded situations, resem- 

 bles Selaginella in general habit, except that the leaves are 

 usually arranged radially. The rliizome runs close to tlie 



_"__ , S 



-U 



ground or in tlie soil, and sends up erect branches. Spo- 



ouT. or lit 



