114 IIOFMEISTER, ON 



of the narrow covering which is closely attached to the 

 calyptra (PL XVI, fig. 20). Viewed from the outside, these 

 processes of the receptacle appear like fleshy appendages of 

 its margin. The number of them is the same as that of 

 the impregnated archegonia, viz., from one to five. (See 

 Bischoffs figures, ' N. A. A. C. L.,' vol. xvii, part 2, pi. 49, 

 figs. 1 4.) 



The tendency of the ventral portion of the archegonium 

 of Rebouillia to develope itself largely is especially remark- 

 able in archegonia just impregnated. Here the multipli- 

 cation of the cells near the central cell is so rapid that the 

 latter becomes a wide, flask-shaped cavity, even before the 

 occurrence of the first division of the germinal vesicle con- 

 tained in its interior. This elongated, ellipsoidal cell lies 

 free in the cavity, entirely imbedded in transparent muci- 

 lage (PI. XVII, fig. IS). 



The fruit-rudiment in Reboivillia, like that of Riccia, 

 Targionia, Marchantia, and Fegatella, exhibits the remark- 

 able species of growth which occurs in the fruit of mosses, 

 although, in other respects, the plants just mentioned 

 are nearer to the Jungermannise than to the mosses. 

 This growth consists in the division of the mother-cell by 

 a strongly inclined septum, and a continually repeated di- 

 vision of the apical cell of the fruit-rudiment by means of 

 septa inclined alternately in two directions. The form of the 

 young fruit-rudiment is very slender (PI. XVI, fig. 19); it 

 is only a double row of elongated cells. The longitudinal 

 growth, however, soon ends ; a considerable multiplica- 

 tion of the cells commences in a diametrical direction, 

 a multiplication which is more active at the apex (the future 

 capsule) and at the base (the growing knobby enlargement) 

 than in the middle (the future fruit-stalk). The increase 

 in the size of the fruit is so considerable at the approach of 

 maturity that it usually entirely destroys the upper part 

 of the calyptra ; it then lies naked in the fleshy sheath 

 formed by the growth of the margin of the receptacle. 

 Fegatella conica developes from six to eight archegonia on 

 the lateral margins of its receptacle (PL XVI, fig. 6). 

 These archegonia are, at an early period, surrounded by the 

 receptacle, which is growing rapidly in breadth. The mass 



