1022 SUMMARY OF CURRENT RESEARCHES RELATING TO 



In tho sporogonium of the Jungermannieae, M. Leclerc du Sablon 

 finds a mechanism of dehiscence Bimilar to that which ho has de- 

 scribed in the case of anthers, except that the epidermis sometimes 

 takes part in causing the dehiscence along with the subjacent layers. 

 The elaters, by adhering to the walls of the sporogonium, form a kind 

 of brush which sweeps out the spores as the valves curve. The 

 structuro and dehiscence of the sporogonium are described in the 

 cases of Jungermannia bicuspidata and alicularia, Calypogeia Tricho- 

 manis, Aneura pingnix, Veil in ejiiphi/lhi, Fndlauia dilatata, Fussombronia 

 csespitiformis, and Targionia hypophylla. 



In tho Riccieae the structure and mode of formation of the spores 

 indicate tho least differentiation of any class of Hepatica^. The mass 

 of the sporogonium continues for a long time to be formed of homo- 

 geneous parenchyma, and it is only at a comparatively late period 

 that the mother-cells of tho spores are set at liberty. In liiccia the 

 elaters are entirely wanting ; in the other Riccieae, e. g. Sphserocarpus, 

 they are represented by sterile cells without ornamentation, each 

 c >rrcsponding to a single spore. The walls of the sporogonium, 

 composed of a single layer of cells without ornaments, do not 

 dehisce in the proper sense of the term, but are irregularly torn at 

 maturity. 



In the Targionieae and Marchanticae the elaters are well developed, 

 and are furnished with several spirals. The sporiferous tissue also 

 remains long in a parenchymatous condition ; but as soon as the 

 central walls are resorbed, the mother-cells of the spores are clearly 

 differentiated from those of the elaters. In the Targionieae and the 

 greater number of the Marchantieae the elaters are intermingled with 

 the spores, and do not play any appreciable part in the dehiscence 

 of the sporogonium. The walls of the sporogonium-cells are orna- 

 mented, but there is no regular dehiscence. 



In the Jungermannieae the differentiation of the spores and elaters 

 takes place at a much earlier period. In respect to the elaters, the 

 thalloid genera, like Peliia and Aneura, show a lower type than the 

 foliose genera like Jungermannia and Frullania. In the latter an 

 elater corresponds to a row of spore-mother-cells. It is also in the 

 Jungennannieae that we have the most complicated structure in the 

 walls of the sporogonium. They are composed of two layers of cells 

 furnished with ornaments in such a way that, except in Fossombronia, 

 the sporogonium dehisces regularly by four valves ; and in this group 

 also the foot of the sporogonium is most strongly developed. 



Taken as a whole, the characters observed in the asexual genera- 

 tion tend to confirm the classification of the Hepaticas derived from 

 the vegetative characters and those of the sexual generation. 



New Species of Metzgeria.* — Mr. W. Mitten describes three 

 new species of this genus of Hepaticae, Metzgeria saccata from New 

 Zealand, M. seobina fro n Borneo, and M. nitida from Australia, the 

 first differing from all species hitherto known in the presence of 

 saccate lobules to the frond. 



* Jouni. Linn. Soc. Lond. (Bot.), xxii. (188G) pp. 241-3 (3 figs.). 



