CRYPT0GA2IS 



209 



356. 



The macrospore 

 with prothallium 

 (p) bearing ar- 

 chegonia at the 

 time of fertiliza- 

 tion. 



— Campbell. 



of Selaginella spores. In the microspore these cells, 



filling the whole interior, compose an anthericlium, with 



only the slightest rudiment of a prothallium ; and 



within this antheridial body are formed antherozoids. 



In the macrospore a reduced prothallium appears. Tliis 



finally increases sufBciently 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, when 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 be particu- 

 larly noted with regard to the repro- 

 duction of Selaginella : 



(1) Spores are of two kinds as regards (a) origin, (li) size, 

 (c) ultimate development. For they originate in different 

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

 rise to antheridia and archegonia, respectively. This con- 

 dition is foreshadowed in the Ferns, of which some species 

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

 the differentiation extends to the spores and sporangia. 



(2) The gametophyte (prothallial structure) is reduced 

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

 lost all independence, possessing neither chlorophyll nor 

 rhizoids. 



488. Other Pteridophytes Avhich one will frequently 

 see are Lycopodiiim^ the Club Moss, and Equisetum^ the 

 Scouring Rush or Horsetail. 



489. Lycopodium (Fig. 357), to be met with in woods 

 and old pastures and in partly shaded situations, resem- 

 bles Selaginella in general habit, except that the leaves are 

 usually arranged radially. The rhizome runs close to the 

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



OUT. OF BOT. 14 



