On the Gemma of Bryum androgynum. 227 



contact with the saucer, into which water was poured, but only in 

 quantity sufficient to preserve the gauze in a moist state ; several 

 entire gemmiferous heads of Bryum were then placed upon the gauze 

 over the centre of the watch-glass, and the whole apparatus was 

 kept in a moderately warm place not exposed to very bright light, 

 and covered with a bell-glass. After some days some of the gem- 

 mas were detached and examined with a magnifier ; it was found 

 that the contents of many had undergone a remarkable change. 

 The green granular matter had nearly disappeared, and the cavity 

 of each seemed now to be divided by several dark green partitions, 

 (Fig. 6,) and many of them presented a swelling near that part by 

 which they were attached to the cords, (Figs. 7 and 8.) At the end 

 of from fourteen to twenty days, it was observed that in many a 

 small transparent nearly cylindrical tube had been protruded from 

 the part which some days previously had presented a swelling ; 

 Figs. 9, 10, 11, represent this appearance. It was not confined 

 entirely to those whose granular matter had disappeared, for many 

 in which this was still visible had begun to germinate, and the tube 

 in some cases contained a portion of it. This tube or filament was 

 invariably protruded from the same part in every gemma, and 

 never more than one made its appearance in each. The filaments 

 seemed to be not merely a prolongation of the membrane of the 

 gemma, but appeared to have proceeded from its interior, and to 

 have burst the membrane. In only one instance did I remark that 

 the protruded filament presented an articulated appearance, or ra- 

 ther its interior seemed to be divided by several septse. After re- 

 maining more than a month upon the moist gauze, the gemmae had 

 made no further progress in germination. This might have been 

 owing to the gauze not presenting a proper medium for their growth, 

 or perhaps rather from exposure to too strong light ; at the end of 

 this time also, the green fecula had disappeared in all of them, and 

 they resembled Fig. 6. While engaged in these observations, I re- 

 marked, that a leaf of Bryum, which had accidentally fallen on the 

 gauze, and remained there for some time, had thrown out several 

 slender transparent radicles near its place of attachment to the stem, 

 and from the angle between the midrib and the limb of the leaf. 

 May not this be another way in which B. androgynum is propagated? 

 or even this may be true of every moss. Sir W. J. Hooker says, 

 (British Fl. Vol. ii. p. 74,) that from the points of the leaves of 

 Hookeria lucens roots are often emitted. 



