REPRODUCTION OF CRTPTOGAMIA. 755 



pregnation takes place by the contact of the spermatozoids 

 with the germ- cell of the archegonium, which immediately de- 

 velopes and forms the embryo, from which a leafy stem bearing 

 fructification is ultimately produced. 



6. Equisetacece or Horse-tails, and 



7. Filices or Ferns. — The mode of reproduction of the plants 

 of these two orders is essentially the same, and we shall ac- 

 cordingly allude to them together. As already fully noticed 

 (see pp. 369 — 372), their leafy structures bear sporangia in 

 which the spores are enclosed {figs. 783 and 787 — 789). There 

 is, however, but one kind of spore. 



The germination of these spores has already been noticed 

 (p. 369), but it will be better for us to refer to it again in this 

 place. In germination, these spores form ultimately a thin, flat, 

 green parenchymatous expansion {figs. 784 and 1108, 6), which 

 somewhat resembles the permanent thallus of the Hepaticaceae 

 {figs. 808 and 810). Upon the under surface of this structure we 

 have ultimately formed, in the Filices, both anther idia and arche- 

 gonia; but in the Equisetacece, the antheridia and archegonia have 

 only been found on separate pro-thalli, and hence these plants 

 would appear to be dioecious. The antheridia {fig. 785) contain 

 a number of minute cells called sperm-cells {se), each of which 

 contains a spirally wound ciliated spermatozoid {sp). The 

 archegonium {fig. 786), is a little cellular papilla, having a 

 central canal, which when mature is open. At the bottom of 

 the canal is a cell called the embryo-sac, in which a germ-cell or 

 embryo-cell is developed. According to other observers, this so- 

 called embryo-cell is simply a germinal corpuscle till after fertiU- 

 zatiou, — that is, a free primordial utricle, with- 

 out an external wall of cellulose. 



When mature, the upper part of the an- 

 theridium separates from the lower, something 

 like the lid of a box ; the sperm-cells then 

 escape, become ruptured, and emit their con- 

 tained spermatozoids. These spermatozoids 

 make their way down the canal of the arche- 

 gonium to the embryo- sac, by which the 

 contained germ-cell, embryo-cell, or germi- 

 nal corpuscle, is fertilized. This embryo-cell 

 then developes, and the embryo thus formed ^. „„„ 



^^ .' J •' Fig. 1108. — a, young 



continues to increase, and soon possesses gporangiferous plant 



rudimentary leaves and roots {fig. 1108), ?pte;.'|farisi? from 



and ultimately produces a plant with fronds an embryo pnfduced 



bearing sporangia, which resembles the one ^J impregnation in 



.. 1 • 1 ^1 • • n 1 . • 1 the archegonium of 



from which the spore was originally obtained, the pro-thaiius, b. 

 The Ferns and Horse-tails, as already noticed 

 (pp. 371 and 372), are thus seen to exhibit two stages in their 

 growth; in the first of which the spores produce a thalloid ex- 

 3 c 3 



