MUSCINE^E 



in rows directed upwards, but not actually reaching the epidermal layer 

 of cells through which the stomates penetrate ; while beneath them is 

 the non-chlorophyllous layer, consisting of cells longest in the hori- 

 zontal direction without intercellular spaces. Each stomate has a number 

 _,__ of guard-cells formed by 



radial cell-divisions. The 

 details in the structure of 

 the stomates differ in the 

 different genera. Leitgeb 

 describes them as of two 

 kinds, simple and canali- 

 culate. The former are 

 epidermal pores situated 

 immediately above the air- 

 chambers ; the latter, which 

 occur in Marchantia and 

 Preissia, have the ap- 

 pearance of canals exca- 

 vated in the surface of the 

 thallus. Some of the rhi- 

 zoids of Marchantia are 

 characterised by singular 

 internal thickenings to the 

 cell-wall. The peculiar non- 

 sexual organs of propagation 

 of Marchantia, Lunularia 

 (Mich.), and other genera, 

 known as cupules, have 

 already been described (figs. 

 150,155). A peculiar non- 

 sexual mode of propagation 

 by means of gemmae occurs 



FIG. 158. Development of archegone of M. polymorpha. in Fegatella (Radd.). 

 (x 300). IV, before, VI VIII, after fertilisation, e, 

 central cell with oosphere ;f, young embryo ; si, lowest cell 

 of axile row ; //, perigyne. IX, immature sporogone in 



venter of archegone ( x 30) ; a, neck of archegone ; st, 

 stalk of sporange which contains young spores and elaters. 

 ( After Goebel.) 



The sexual reproductive 

 organs of the Marchanti- 

 aceaa are, in most of the 

 genera, borne on erect 

 branches of the thallus of a peculiar umbrella-like form, which have been 

 variously termed receptacles, discs, and inflorescences. They may be male, 

 female, or bisexual ; and, when unisexual, the species may be monoecious 

 or dioecious. In Fegatella the male inflorescences are oval discs sessile 

 upon the thallus (fig. 152). The inflorescence is generally regarded 



