288 THE GAMETOPHYTE, AND SEXUAL ORGANS [CH. 



a b d 



Fig. 278. a — d= Marattia Dotiglasii, after Campbell. e—f= Ophio- 

 glossuvi pendidiim, after Lang. « = antheridium, with divisions of 

 spermatocytes (32) in section, perhaps not complete; ^ = young 

 antheridium ; c = archegonium ; d= young archegonium ; e = anthe- 

 ridium with 88 spermatocytes in section ; /= archegonium. 



requirements that it is standardised throughout the Class. Such standardi 

 sation has also been achieved by the embryo-sac 

 of Angiosperms, which takes an equally essential 

 part in propagation, and shows uniformity of its 

 contents comparable with the uniformity of the 

 contents of the archegonium in Ferns. The only 

 variable characters of the archegonium available 

 for comparison will therefore be the number of 

 cells of the neck, and the degree of its projection 

 beyond the general level of the prothallial tissue. 

 A comparison of the sunken archegonia oi Marat- 

 tia and Ophioglossmn (Fig, 278, c,f) with that of 

 Matteuccia (Fig. 279) will show the range of vari- 

 ability in this respect. Naturally the development 

 of the archegonium is also uniform. The whole 

 archegonium originates like the antheridium from 

 a superficial mother-cell (Fig. 278, d). This first 



Fig. 279. Mature archegonium 

 of Matteuccia Struthiopteris, 

 after Campbell. ( x 250.) 



