THE HIGHER CRYPTOGAMIA. 67 



Madotheca platyphylla exhibits a remarkable peculiarity. 

 The cells of the covering layer not only divide very fre- 

 quently by septa perpendicular to the outer surface, so that 

 they appear proportionally small and very numerous in 

 the perfect antheridium ; but the lateral cells and those 

 underneath the central cell divide also by septa parallel 

 to the outer surface of the young antheridium ; the 

 upper ones once, the lower ones several times over. 

 By this means the antheridium acquires a consider- 

 able size; the oval group of cells in which the sperm- 

 atozoa are produced occupies only a small portion of its 

 upper half. The covering of this group of cells consists 

 also always of a single layer of cells (PL VII, fig. 5). The 

 walls of the cells of the covering-layer are coloured a bluish- 

 red by iodine. 



The spermatozoa in the leafy Jungermannise are con- 

 siderably smaller than those of Pellia. Fossombronia 

 pusilla has the largest of all those which I have examined ; 

 the diameter of the vesicles in which they originate is 

 s—"' ; those of the diminutive Jungermannia divaricata 

 are a little smaller (PI. VII, fig. 21) ; those of Frullania 

 dilatata and Madotheca platyphylla are very small (PI. VII, 

 fig. 6; PL XI, fig. 42). 



The development of the archegonia of the leafy liver- 

 worts corresponds exactly with that of the like organs in 

 Pellia, the Marchantia?, and the mosses. In Fossombronia 

 and Haplomitrium these organs are produced in the axils of 

 leaves ; in the other genera treated of in this chapter they 

 are found only on short lateral branchlets. In growing 

 archegonia, however, the peculiar condition which occurs 

 in Pellia and the mosses is seldom seen. In Pellia and 

 the mosses it often happens that the formation of the cells 

 of the axile string does not extend as far as the cells im- 

 mediately adjoining the apical cell, a fact which is doubt- 

 less to be attributed to the slow, and consequently relatively 

 limited development of the neck of the organ. The arche- 

 gonia of the true Jungermanniae, and of Radida complanata, 

 are proportionately short and uniformly thick (PL VII, 

 figs. 14, 15 ; PL VIII, figs. 1, 2 ; PL X, fig. 1 ; PL XI, 

 fig. 1) ; those of Possombronia (PL VI, figs. 29—33) 



