96 



THE BIOLOGY OF A PLANT. 



by a partition from the original cell (Fig. 60). Further divisions 

 then follow in the dome-shaped cell such that a central cell is left, 



surrounded by a layer of peripheral 

 cells (Fig. 61). By repeated divisions 

 the central cell splits up into the 

 spermatozoid mother-cells (Fig. 59). 

 Within each mother-cell the proto- 

 plasm arranges itself in a peculiar 

 spiral body, the spermatozoid, which 

 is the male germ-cell. 



When the mature antheriditnn is 

 moistened, the peripheral cells swell 

 and thus press out the mother-cells and 

 spermatozoids (Fig. 62). The latter escape from the mother- 

 cells and swim about very actively in the water. They appear 

 as naked single cells, of a peculiar corkscrew shape, and bear 



upon the finer spirals numerous 

 extremely active cilia (p. 31), by 

 which they are driven swiftly 

 through the water. 



FIG. 61. (After Hofmeister.) Lat- 

 er stage in the development of an 

 antheridium of Pteris serrulata. 

 p, peripheral cell; c, central cell 

 from which the spermatozoid 

 mother-cells arise. 



FIG. 62. (After Luerssen.) Bursting of 

 the antheridium and escape of the sper- 

 matozoids. an, antheridium; m.c, sper- 

 matozoid mother-cells; sp, spermato- 

 zoids. 



FIG. 63. (After Strasburger.) Mature 

 archegonium, showing the oosphere 

 (o), the neck (n), and mucus (m) is- 

 suing from the mouth of the canal. 



The Archegonia, or female organs (Figs. 58, 63), described for 

 the first time by Suminski in 1864, likewise arise from single su- 

 perficial cells of the prothallium. They are situated almost exclu- 



