THE HIGHER CRYPTOGAMIA. 155 



cells (PI. XVIII, fig. 12), in each of which a spirally 

 folded spermatozoon is produced in the interior of a len- 

 ticular vesicle. The cells which surround these central 

 cells multiply by division, which takes place by means of 

 septa perpendicular to the outer surface, and become the 

 covering layer of the antheridium. On their outer side 

 there is formed a glassy, transparent, very tough cuticle, 

 which may be easily detached. When the organ is ripe 

 the cuticle bursts at the apex ; the vesicles enclosing the 

 spermatozoa, having become free by the dissolution of the 

 walls of their mother- cells escape at the opening, disperse 

 themselves when under water in the surrounding fluid, and 

 set the spermatozoa free, which then commence their 

 revolving motion. Their spiral has from two and a half 

 to three turns, and is sometimes a right-handed, some- 

 times a left-handed one. The anterior end of the sper- 

 matozoon carries two thin motile cilia attached laterally 

 (PL XVIII, fig. 13). The covering cells* of the antheridia 

 usually become isolated after maturity, like those of Antho- 

 ceros, Fossombronia, &c. ; the cuticle holds together for a 

 considerable time. 



Schleiden was of opinion that the antheridium of Sphag- 

 num was a large sac-like cell, in whose fluid contents the 

 vesicles which produce the spermatozoa swam about freely. 

 This notion is quite erroneous. Until just before matu- 

 rity, the walls of the small, tessellated, closely-packed cells 

 remain quite intact, each of them enclosing one of the 

 vesicles. The nature of their arrangement is such, that the 

 directions of the primary divisions of the seven-surfaced 

 central cell of the very young antheridium may be easily 

 recognised. 



Fruit is developed only in those mosses where the arche- 

 gonia are in the neighbourhood of antheridia. Any Botanist 

 paying attention to the growth of mosses will be able to 

 produce instances, in addition to those afforded by the older 

 observers, to prove that female dioecious mosses, in whose 

 neighbourhood no male plants of the same species occur, 

 produce perfect archegonia, but never fruit. At Leipzig, in 



* The chlorophyll granules of these cells do not change colour when the 

 antheridium is ripe. 



