SECT. VI. 



MAR CHANT I A CE^. 



3*9 



Fig. 45. Marchantia polymorpha : 



certain objects called archegonia (fig. 45) are found to 

 be concealed between membranes wliich connect the 



spokes of the whorl at their 

 origin. These archegonia are 

 shaped like flasks with 

 long necks, and each 

 has a germ cell in its 

 interior, into which a 

 canal leads down from 

 the extremity of the 

 neck. When this em- 



bryO Or germ Cell is 



fertilized by the sper- 



matozoids, instead of producing a new plant 

 resembling its parent, the embryo cell developes 

 itself into a sporangium containing spores, which 

 are isolated cells enclosed in firm yellow en- 

 velopes and elaters, or ovoidal cells, each con- 

 taining a double spiral fibre coiled up in its 

 interior. This fibre is so elastic, that when the 

 surrounding pressure is withdrawn by the burst- 

 ing of the sporangium at maturity, the spires 

 suddenly extend themselves with such force as 

 to tear open the cell membrane, and jerk forth 

 the spores which may be adhering to their coils, 

 and thus to assist in their dispersion. The 

 spores, when they germinate, develope them- 

 selves into little collections of cells, which 

 gradually assume the form of a flattened frond. 2 

 It is only when exposed to light and air that 

 the Marchantias have regular fructification ; in Marchantia - 

 shady places they are reproduced by buds placed in open 

 conceptacles, which are formed out of green globules 

 that appear in different parts of the frond, and after 

 a time split open at the summit and expand into 



2 Tr. Carpenter's ' Microscope.' 



Fig. 46. 



