80 HOFMEISTER, ON 



calyptra in many liverworts (which is produced by the 

 multiplication of the cells of the apex of the stem), and the 

 vaginula of the mosses. In Radula complanata, for in- 

 stance, the base of the calyptra is not less remarkably 

 conical and fleshy than in Phascum. This multiplication 

 of the cells underneath the impregnated archegonium in 

 the direction of their thickness, is very active in Radula 

 complanata, less so in Lophocolea and the true Junger- 

 mannise ; lastly, in Frullania dilataia it is entirely 

 wanting ; here the multiplication of the cells is limited 

 exclusively to the ventral portion of the impregnated arche- 

 gonium, towards the base of which it diminishes con- 

 siderably. The form of the calyptra in this species is 

 flask-shaped in all stages of its growth ; it is narrowly 

 constricted at the base (PL XII, figs. 3, 5). 



The lower, reduced end of the rudimentary fruit, extends 

 downwards to the same distance as the cell-multiplication 

 beneath the impregnated archegonium extends upwards 

 into the tissue of the stem (PL VIII, fig. 6 ; PL XI, fig. 4). 

 The arch of the basal cell of the end of the stem often 

 exhibits a marked thickening of its wall (PL VIII, figs. 

 4, 5) ; perhaps it is by means of this that it acquires 

 sufficient firmness to penetrate the cells of the yielding 

 tissue which lies in its way. In Frullania dilataia the 

 cavitjr of the calyptra, which encloses the young rudi- 

 mentary fruit enlarges soon after impregnation by a mul- 

 tiplication of the cells of its walls, often so rapid aiid con- 

 siderable, that the growth of the rudimentary fruit cannot 

 keep pace wuth the increase in circumference and height of 

 the cavity, which is filled with mucilage ; at this period 

 the young fruit often lies quite free in the interior (PL XII, 

 fig. 4). 



Gottsche observes a similar phenomenon in Calypogeia 

 Trichomanes* I have convinced myself by an observation 

 made in 1853, that in Calypogeia, also, the development of 

 the impregnated germinal vesicle normally follows step by 

 step the great enlargement of the central cell of the arche- 

 gonium, which is produced by the multiplication of its 

 neighbouring cells. Both developments are slow, that of the 

 * L. c, T. xsx, f. 8, 11. 



