THE HIGHER CltYPTOGAMIA. 301 



At this time or a little later tlie recurved cells of the 

 aperture of the archegonium shrivel and fall off. The four 

 elongated cells of the neck of the archegonium upon which 

 they are borne also lose their vitality. Their walls, so far 

 as they form the canal of the archegonium, assume a dark 

 brown colour. 



The number of the archegonia of a vigorously developed 

 prothallium varies from twenty to thirty ; it exceeds there- 

 fore that of the antheridia of even the largest male prothallia. 

 Usually more than one archegonium is impregnated. I 

 counted as many as seven embryos in one and the same 

 prothallium. The brown colour of the unimpregnated 

 archegonia extends not only over the walls of the whole 

 canal — which remains open — but also over the central cell 

 and its contents (PI. XXXVIII, fig. 3). 



The first axis of the embryo (which remains undeveloped) 

 has its origin in a series of repeated divisions of the terminal 

 cell commencing in the three-sided cell which includes the 

 lower end of the embryo rudiment (PL XXXVIII, 

 figs. 7—10 ; PI. XL, figs. 1—3). The cells of the second 

 degree divide at first only by longitudinal and transverse 

 septa perpendicular to the free outer surfaces (PL XXXVIII, 

 figs. 7,8; PL XXXIX, fig. 1) ; at a later period septa, 

 parallel to these surfaces make their appearance and form 

 inner cells. A similar cell- multiplication commences in the 

 one lateral cell of the 4-cellular-ernbryo-rudiment. The 

 lines in which the first septa of the lateral cell intersect are 

 parallel to the longitudinal axis of the archegonium (PL 

 XXXVIII, figs. 7—10). A side shoot of the embryo is 

 thereby formed — the second axis of the germ plant, its 

 first leaf-bearing shoot. By the considerable growth in 

 thickness of the primary axis below the place of origin 

 of the secondary one, and still more by the upward curva- 

 ture of the latter during its development, the rudiment of 

 the secondary shoot is soon brought almost to the 

 apex of the globular cellular mass which now constitutes 

 "the embryo — to within a small distance from the locus of 

 the lower end of the canal of the archegonium which is now 

 entirely obliterated (PL XXXIX, figs. 4, 5). 



Up to this stage the rudiment of the embryo may be 



