242 



BOTANY 



buds, or gemmae, which may be produced in large numbers. It also 

 bears mono3ciously or diceciously the sexual organs. 



Archegonium. The sexual organs of the Pteridophytes are similar 

 to those of the Bryophytes. The Archegonium (Fig. 206) has the 

 venter imbedded in the tissue of the gametophyte, and the neck has 

 but four rows of peripheral cells. The four rows of neck-cells prob- 

 ably represent a further development of the four cover-cells of the 

 archegonium of the Liverworts. Of the Bryophytes, the Anthocero- 

 tales come nearest the lower Pteridophytes in the character of the 

 sexual organs. Except in Lycopodium, where the number of canal- 

 cells is larger, the neck shows but two canal-cells in the Pterido- 



B 



FIG. 206. Struthiopteris Ger- 

 manica, open archegonium 

 (X300); o, the egg. 



FIG. 207. Osmunda Claytoniana. A, ripe an- 

 theridium. B, the same discharging the sperm- 

 cells (X 400). C, spermatozoids (X 800). 



phytes. The ventral canal-cell is always present, and as in the 

 Bryophytes is the sister-cell of the egg. 



Antheridium. The antheridium (Fig. 207) in the lower types, such 

 as Lycopodium and Marattia, is buried in the prothallial tissue as it 

 is in Anthoceros. In the more specialized Ferns it projects and 

 forms a nearly spherical body, whose Avail is composed of a single 

 layer of chlorophyll-bearing cells, within which is a mass of colorless 

 sperm-cells. In the Club-mosses, the small spermatozoids are bicili- 

 ate like those of the Bryophytes ; in the Ferns and Horsetails they 

 are larger, and have many cilia. 



The development of the spermatozoids (Fig. 208) has been fol- 

 lowed in several Ferns and in Equisetum. In the later divisions 



