[62 



SECOND GROUP. — MUSCINEAE. 



younger than the one next inside it. The antheridia are formed from superficial cells, 

 but they are sunk in the upper side of the receptacle and are arched over by the 

 surrounding tissue. The first archegonia also are formed on the upper side of the cap- 

 like receptacle but are brought round to the under side by the further growth of the 

 receptacle (Figs. 114, 115). The stalk of the receptacle is still quite short when 

 fertilisation takes place, but afterwards elongates, and thus materially facilitates the 

 dispersion of the spores, the stalk of the sporogonium being itself very short. The stalk 

 of the receptacle would appear therefore in 

 this case to do the work of the stalk of the 

 sporogonium in the Jungermannieae and the 

 Mosses. The archegonia appear on the disk 

 which surmounts the stalk and are directed 

 downwards or outwards. The form of the 

 part that bears the archegonia varies much, 

 and the mode in which the archegonia are 

 enveloped in involucres or perigynia is equally 

 various. As it is impossible to describe all 



^k^r^"^^ 



Fig. 



Fig 114. Female receptacle of Marchnn 

 vwypha seen laterally from below; st stalk with two 

 ventral channels, ."• the radiating outgrowths from 

 the receptacle, pc the envelope between them, / spo- 



these things in a brief space, Marchantia 

 polynicn^pha, the species most fully provided 

 in this respect, may serve as an example. 

 The explanation of the figures will make the 

 chief points sufficiently clear. 



The capsule of the sporogonium of the 

 Marchantieae, which is in most cases shortly 

 stalked, contains elaters, which radiate from 

 the base of the capsule to the circumference 

 (Fig. 100, IX) ; it either opens at the apex 

 by numerous teeth or by four lobes, or the 

 upper part separates as a lid by a circular fissure. 

 the peculiar gemmae and their receptacles. 



The branching of the thallus is either dichotomous, as in the thalloid Jungermannieae, 

 or by formation of shoots on the under side ; the one or the other form is the more 

 prominent in dififei ent genera ; Marc/iatitia, Lunulafia, and Fegatella form many 

 bifurcations and scarcely any ventral shoots. In Targionia and many species of 

 Fimbriaria the latter form of branching prevails ; in others, as in Plagiochasma, both 



Maychantia polymorpJuz. A perpeiuii- 

 cular longitudinal section through a female receptacle 

 hu ; bb scales. It rhizoids in the channel of the stalk, 

 g mucilage-cells between the air-caviiies of the upper 

 side. B half of the ground-plan of an older receptacle 

 and of its stalk st ; chl the green tissue of the receptacle, 

 g large hyaline cells, pc the common envelope-leaves 

 {pc in Fig. 114), a archegonia with their oosphores un- 

 fertilised, // perianths of fertile archegonia. C verti- 

 cal tangential section through the receptacle ; a two 

 archegonia, pc common envelope of the archegonia 

 tperichaetium). 



Mention has already been made of 



