HEPA TICM. oOQ 



without the production of a ventral row of leaves, as in Jungprmannia hicuspidata and 

 other Jungermannieae with leaves in two rows. In those especially belonging to the 

 section Trichomanoideae the fertile branches have an endogenous origin, and break 

 out from the older parts of the stem as adventitious shoots ; probably, however, their 

 mother-cells always originate regularly in acropetal succession in the primary meristem 

 of the vegetative cone, as in Mastigobryum and Lepidozia (like they do in Equise- 

 tacese). Finally, according to Leitgeb, the whole branching of many Jungermannieae 

 appears to depend exclusively on the endogenous production of branches. 



The reproductive organs are distributed monoeciously or dioeciously, and are formed, 

 in the thalloid genera, on the dorsal side of the shoot ; in the foliose Jungermannieee at 

 the end of primary shoots or of special small fertile branches, which commonly have an 

 endogenous origin on the ventral side. The antheridia are usually in the axils of the 

 leaves, singly or in groups. The archegonia appear generally in large numbers at the 

 summit of the shoot, either on those which bear antheridia below, or on special female 

 branches, which in the Geocalyceas are hollowed out in such a manner that the arche- 

 gonia are sunk in a deep pitcher-shaped hollow, an arrangement which may be com- 

 pared, to a certain extent, with the structure of a fig. This occurs in an especially 

 striking manner in Calypogeia. Where this peculiar enveloping of the archegonia does 

 not occur, they are concealed by the nearest leaves (the PerichcEtium) • and a Perianth is 

 usually formed in addition, which grows round the 

 archegonia as a special membranous envelope. 

 The development of these organs has been ac- 

 curately described by Leitgeb in the case of 

 RadiiJa complanata (Fig. 224). The primary and 

 lateral shoots both bear, as a rule, both kinds of 

 reproductive organs ; such a shoot is always at 

 first purely vegetative, but forms after a time 

 antheridia, and finishes with a female inflores- 

 cence. Less often, however, it again recurs, after 

 the production of antheridia, to a vegetative de- 

 velopment. The antheridia of Radula are meta- 

 morphosed trichomes ; they stand singly in the 

 axils of the leaves, and are completely enclosed 



in the hollow formed by the very concave lower ^..i;"/:f;-;he,ro:r."r/JfntK:::ir; 

 lobe of the leaf. They arise from the club- * leaf (after Hofmeister). 

 shaped protuberance of a cell belonging to the 



cortex of the stem and lying before the leaf at its base. The female inflorescence 

 of Radula always stands at the end of the primary or of a lateral shoot, and contains 

 from three to ten archegonia, surrounded by a perianth, which is again enveloped by 

 a perichaetium of two leaves. The whole female inflorescence (the archegonia together 

 with the perianth) is developed from the apical cell of the shoot and from its three 

 youngest segments. The archegonia arise from the apical cell itself, and from the 

 upper parts of its lateral segments ; the lower parts, together with the ventral seg- 

 ment, are employed in the formation of the perianth. The further development of the 

 archegonia and antheridia has already been described. 



In the species examined by Hofmeister the fertilised oosphere is first divided by a 

 septum, /. e. at right angles to the axis of the archegonium. Only the upper of the two 

 cells, the one towards the neck of the archegonium, becomes further divided ; it 

 becomes the apical cell of the sporogonium, and is sometimes again divided transversely 

 once or twice before a longitudinal wall makes its appearance in it ; the two cells thus 

 formed are finally divided into four apical cells arranged as octants of a hemisphere. 



The basal portion of the growing archegonium becomes swollen out and pene- 

 trates down into the tissue of the stem, being nourished and firmly enclosed by it (the 

 Vaginula). As soon as the young sporogonium consists of a number of cells, its wall 



