340 XXV. REPRODUCTION OF THE BRYOPHYTA. 



which swells into mucus. Between these papillae are also found 

 some which are two-celled ; and some also, the upper cell of 

 which has been further cross-septate. The lower cell remains 

 simple, and forms the pedicel (or stalk) ; the cells of the upper 

 portion soon again divide longitudinally, and the structure be- 

 comes constantly more multicellular, enlarges much tangentially, 

 and becomes several cells thick in the middle. Others will be 

 found which have attained their ultimate biscuit-like or bi-convex 

 form as fully-developed gemmae, The unicellular pedicel can 

 easily be broken through. The separation of the gemmae, and 

 their ejection from the cups, results from the strongly-swelling 

 mucus, which is developed from the unicellular club-like papillae 

 at the bottom of the cup. Each of the two lateral indentations of 



ft* 



FIG. 122. A, a portion of a thallus of Marchantia poly niorpha (t), with the upright 

 male receptacle (hit), bearing antheridia. , portion of a thallus with a cupule con- 

 taining gemmae ; w, growing points of the two branches of the thallus. (After Sachs. ) 



the gemma conceals a growing point, protected by short papillae. 

 The cells of the gemma are rich in chlorophyll, but on both sides 

 large colourless cells occur, in the median portions only, but 

 otherwise irregularly scattered. At the edge, individual cells 

 contain oil-bodies. After the dissemination of the gemmae, the 

 large colourless cells develop in one or two days into hair-roots 

 (rhizoids), in all cases on the shaded side of the gemma only, 

 which hence becomes the ventral side, while the side exposed 

 to the light forms morphologically the upper or dorsal side. If 

 the gemma be inverted the new under side similarly becomes 

 ventral, and produces rhizoids. 



Sexual Reproduction of Marchantia. The sexual organs of 

 the Marchantiaceae are situated upon special receptacles, which 

 we will also study in Marchantia polymorpha. Male and female 



