Ill marchantiea: 



47 



in more or less distinct groups or " inflorescences." As might 

 be expected, this is least marked in the lower forms, especially 

 the Corsinieae,^ where the main distinction between them and 

 the lower Ricciaceae is that in Corsinia the formation of sexual 

 organs is confined to a special region, and that the archegonia 

 do not have an individual envelope as in Riccia, but the whole 

 group of archegonia is sunk in a common cavity, which is of 

 exactly the same nature as that in which each archegonium is 

 placed in the latter. In most of the Marchantieae, however, 

 both antheridia and archegonia are borne in special receptacles, 

 which in the case of the latter are for the most part specially 

 modified branches or systems of branches, raised at maturity 

 upon long stalks (Fig. 1 9). The antheridial receptacles are 

 sometimes stalked, but more commonly are sessile, and often 

 differ but little from those of the higher Ricciaceae. 



The sporogonium shows an advance upon that of the 

 Ricciaceae by the development of a lower sterile portion, or foot, 

 in addition to the spore-bearing portion or capsule, and in the 

 latter there are always sterile cells, which in all but the lowest 

 Corsinieae have the form of elaters. At maturity, also, the ripe 

 capsule breaks through the calyptra, except in the Corsinieae, 

 where, too, the sterile cells do not develop into elaters, but 

 seem to serve simply as nourishing cells for the growing 

 spores. The stalk of the capsule is always short compared 

 with that of most Jungermanniacese, and the wall of the capsule 

 remains intact until the spores are ripe. 



The spores vary much in size, and in the development of 

 the outer wall. In Marcliantia polyvwrpha and other species 

 where the spores germinate promptly, the ripe spore contains 

 chlorophyll, and the exospore is thin and slightly developed. 

 In such cases there is no distinct rupture of the exospore, but 

 the whole spore elongates directly into the germ -tube. In 

 Conocephalus, where the spores are very large, the first divisions 

 occur in the spores before they are scattered. In species 

 where the spores do not germinate at once the process is 

 much like that of Riccia, and the thick exospore is ruptured and 

 remains attached to the base of the germ-tube. 



The apical growth of the Marchantieae is very much like 

 that of Riccia. In Fimbriaria Californica (Fig. 13) the apical 

 cells seen in vertical section show the same form as those of 



^ Leitgeb (7), vol. iv. 



