40 



ACADEMIC BOTANY. 



the Arbor Vitce, Cedar, and Pine ; they are therefore 

 called Ground Pines. Their spores are of two 

 kinds, like those of the Marsilea ; they are con- 

 tained in spore-cases wliich grow in the axils 

 of leaves which form special cones. The pro- 

 thallus here is a mere vegetative cell (Fig. 

 41, A) ; it is seen in the macrospore before 

 germination (A, above the line d) ; in germi- 

 nation the root-hairs spring from this prothal- 

 lus; below the line d is the perisperm, fore- 

 shadowing the phanerogam ; the archegonia are ' 

 developed in this prothallus, projecting also into 

 the perisperm which nourishes their embryos, 

 e, e. Antheridia are developed in the germina- 

 ting microspore, and the process of fertiliza- 

 tion is the same as described in the ferns. 

 The embryo, however, is still without dif- 

 ferentiation into parts (Fig. 41, B); it 

 develops its organs only after leaving the 

 spore. This formation of the prothallus in the spore 

 before germination (it is formed, 

 we remember, only after germina- 

 tion in the ferns, etc.) shows the 

 higher development of the Club- 

 Mosses, and is one of the charac- 

 ters wliich place them highest in 

 their class. They 

 grow in all cli- 

 mates, but the 

 finest are 

 found in 

 a moist, 

 warm, 

 even tem- ^•^S 



Fio. 40. — Club- 

 Mo s s {Li/cnpodiwn 

 clavatum). Stems, 

 with fertile spikes. 



perature. 

 71.— 

 Among 

 the Club- 

 Mosses is the Selaginella, of which so many fine species are or- 

 naments of our green-houses ; often climbing; with lace-like 



Fig. 41. — A, Vert. sec. of germiiiuting macrospore of SeluyinelUt Martenrii. 

 Prothallus with root-hairs, above the line d; below this, the perisperm 

 which fills the spore ; e, e, embryos in the iircheponia. ]i, same, further 

 advanced ; two plants with their first leaves, springing from the prothal- 

 lus^. C, microspore, showing the antheridium with ite small prothallus. 



