BRTOPHTTA. \S1 



The arohegones of the common Liverwort are clustered 

 upon special branches, a few centimetres in height. These 

 branches expand into lohed discs at the top, and beneath 

 these the arohegones appear. They grow out as trichomes, 

 and finally consist of a rounded cell (germ-cell) enclosed 

 in a flask-shaped vessel (Fig. 103). 



390. Fertilization takes place in wet weather by the 

 antherozoids swimming to and down the open neck of the 

 archegone. As a consequence, the germ-cell begins divid- 

 ing, and finally develops into a spore-fruit containing many 

 spores, intermixed with spiral threads called elaters. The 

 use of the latter appears to be to aid in the dispersion of 

 the spores (Fig. 103, X). 



391. In most cases the spore-fruits split open to permit 

 the escape of the spores, which soon germinate and pro- 

 duce a thalloid mass; this develops directly into a new 

 plant in the lower forms, and in the higher soon begins the 

 development of a stem and leaves. 



392. There are four or five orders of Liverworts, includ- 

 ing (1) the Crystalworts (Order Ricci- 

 acese), which are terrestrial or aquatic 

 thalloid plants; (2) the Horned Liver- 

 worts (Order Anthocerotese), which are 

 terrestrial thalloid plants with slender 

 spore-fruits (Fig. 104); (3) the Liver- 

 worts proper (Order Marchantiacese), 

 terrestrial thalloid plants, including the Liverwort '"(Aiithoceros 



„ ^. /■»«• 1 ,• 1 laevis), natural size, with 



Common Liverwort (Marchantia poly- spore-fruits, k, k, sput- 



_, -r . trt t^S open. 



morpha) and the Great Liverwort (Co- 

 nocephalus conicus), both large, flat, branching plants grow- 

 ing in moist places about springs, brooks, ditches, etc. ; (4) 

 the Scale-mosses (Order Jungermanniacese, Fig. 101, 11), 



