308 



GEMMIPAROUS CONCEPTACLES OF MARCHANTIA. 



Fig. 178. 



tained within the conceptacles, forming natural grafts (so to speak) 

 upon the stock from which they have been developed and detached ; 

 and many of the irregular lobes which the frond of the Marchantia 



puts forth, seem to have 

 this origin. The very 

 curious observation was 

 long ago made by 

 Mirbel, who carefully 

 watched the develop- 

 ment of these gemmce, 

 that stomata are formed 

 on the side which hap- 

 pens to be exposed to 

 the light, and that root- 

 fibres are put forth from 

 the lower side ; it being 

 apparently a matter of 

 indifference which side 

 of the little disk is at 

 first turned upwards, 

 since each has the power 

 of developing either 

 stomata or root-fibres 

 according to the influence 

 it receives. After the 

 tendency to the forma- 

 tion of these organs has 

 once been given, how- 

 ever, by the sufficiently 

 prolonged influence of 

 light upon one side and 

 of darkness and moisture 

 on the other, any at- 

 tempt to alter it is found 

 to be vain ; for if the 

 surfaces of the young 

 fronds be then inverted, 

 a twisting growth soon 

 restores them to their 

 original aspect. 



274. When this Plant 

 which are favourable to 

 readily produce the true 



Gemmiparous Conceptacles of Marchantia 

 polymorpha : — a, conceptacle fully expanded, 

 rising from the surface of the frond a, a, and 

 containing disks already detached :— b, first 

 appearance of conceptacle on the surface of 

 the frond, showing the formation of its fringe 

 by the splitting of the cuticle. 



vegetates in damp shady situations 

 the nutritive processes, it does not 

 Fructification, which is to be looked for rather in plants 

 growing in more exposed places. Each of the stalked peltate 

 (shield-like) disks contains a number of flask-shaped cavities open- 

 ing upon its upper surface, which are brought into view by a 

 vertical section ; and in each of these cavities is lodged an 



