LIVEE-WOETS SCALE-MOSSES. 



145 



root), which throws up "fronds" or leaves with a 



strong midrib; this midrib is commonly called its 



stalk, but in tropical countries the fern stalk rises 



above ground to the height of 



30 or 40 feet, and then it is 



seen that the ordinary stalks 



are but the midribs of the 



fronds. There are between two 



and three thousand species of 



fern. The fronds open in a 



peculiar manner, unwinding as 



it were from a round ball. 



The "sorri" or seed-cases are 



situated at the back of the 



fronds in little brown spots, 



each of which is found to consist 



of a heap or collection of round 



capsules, and if thess be placed Fern. 



under the microscope they have 



the appearance of little membraneous cases covered 



with net-like markings, and at the upper part a striated 



band of a brown colour, which after a time stretches 



out into a nearly straight line, tearing open the bag 



or capsule, and a number of seeds escape. Ferns grow 



best in damp and shady situations, and will thrive well 



in damp mould under a glass case. 



6. MAECHANTIACE^ (Liver-worts). 



These Liver-worts are much like 

 Lichens, growing between and 

 upon stones near springs and 

 moist places, and forming a 

 broad thallus or root from which 

 grow cup-shaped sporangia or 

 seed-cases. The Marchanta poly- 

 morpka is one of its chief mem- 

 bers. 



Liver-worts. 

 L 



