348 



MUSCINE^. 



leaves and lateral shoots, since Leitgeb's researches show that great morphological 

 differences occur in the different genera. For the same reason very little of a 

 general character can be said, in addition to what has been mentioned above, on 

 the habit and anatomical nature of the vegetative body, which must therefore be 

 considered under the separate families. 



The Asexual Propagation of Hepaticse is often brought about by the dying off 

 of the thallus or stem from behind, the branches thus losing their connexion and 

 becoming independent. Adventitious branches, arising in the thalloid forms from 

 cells of the older marginal parts, become detached in a similar manner. The 

 propagation by gemmcE is very common and characteristic ; not unfrequently a 

 number of cells of the margin of the leaf of foliose Jungermannieae {e.g. in Mado- 

 thecd) simply detach themselves as gemmae ; in Blasta, on the other hand, as well as 

 in Marchantia and Lunulana, peculiar cupules are formed on the upper side of the 

 flat shoots exposed to the light, which are fiask-shaped in Blasia^ broadly cup-shaped 



Fig. 233. — Marchantia folymorpha ; A, B young 

 shoots ; C the two shoots which result from a gemma, 

 with cupules ; -v v the depressed apical region : D a 

 piece of the epidermis seen from above : sj> stomata 

 on the rhomboid plates (A—C X slightly; D more 

 strongly). 



FIG. 234.— Development of the gemmae 

 Marchantia, 



of 



in Marchantia, crescent-shaped and deficient on one side in Lunularia. From the 

 bottom of these cupules shoot out hair-like papillae, the apical cells of which be- 

 come transformed into a mass of considerable size constituting the gemma. (See 

 Figs. 233, 234.) From the two depressions which lie right and left on the margin 

 of the lenticular gemma (Fig. 234, F7) spring the first flat shoots (Fig. 233, B,, C), 

 when the gemmae have fallen out of the cupule and lie exposed to light on damp 

 ground. 



The Sexual Organs are developed, in the thalloid forms, on the upper side 

 exposed to light; in Anthoceros in the tissue of the thallus itself (endogenous) ; in 

 the other thalloid forms from cells which project like papillae and are of definite 

 origin in reference to the segments of the apical cell. In the Marchantieae branches 

 of a very peculiar shape, which have a tendency to shoot upright from the flat 

 stem, are formed, producing the antheridia on the upper, the archegonia on the 

 under side ; the male and female receptacles may be distributed either monoeciously 



