-:g. 



MUSCINEJE. 



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

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

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

 the habit and anatomical nature of the vegetative structure, \vhich must therefore 

 be considered under the separate families. 



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

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

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

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

 gation by Gemmae is very common and characteristic ; not unfrequently a number 

 of cells of the margin of the leaf of foliose Jungermannieae {e. g. in Madotheca) 

 simply detach themselves as gemmse ; in Blasia, on the other hand, as well as in 

 INIarchantia and Lunularia, peculiar cupules are formed on the upper side of the flat 

 shoots exposed to the light, which are flask-shaped in Blasia, broadly cup- shaped in 



Fig. 212 — Marchantia polyiiiorpha ; A,B younjj 

 siioots; C the two shoots which result from a g-ennna, 

 with cupules; vv the depressed apical region; Z) a 

 piece of the epidermis seen from above ; sp stomata 

 on the rhomboid plates (./-C'X slightly ; D more 

 strongly). 



Fig. 213. — Development of the gemmae 



Marchantia. 



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 w'hich be- 

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

 Figs. 212, 213.) From the two depressions which lie right and left on the margin 

 of the lenticular gemma (Fig. 213, VI) spring the first flat shoots (Fig. 212, B, C), 

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

 ground. 



The Sexual Organs are formed, 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 M'hich project Hke 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 



