698 



THE SUBDIVISIONS OF THE VEGETABLE KINGDOM. 



Antherocerotaceoe. — The oophyte has the form of a little lobed disc, in depres- 

 sions of the surface of which the antheridia and archegonia are sunk. The sporo- 

 gonium is long and cylindrical, and is invested in a circular sheath at its base. The 

 spore-layer has the form of a hollow cylinder, leaving a sterile, central strand of 

 tissue (the columella). Elaters are present amongst the spores, and serve as 

 nutritive tissue for them rather than as instruments of dispersal. In this group 



Jungermanniaceae. 



1 Frullania dilatata growing on the bark of an Acer. 2 a small portion of this plant enlarged ; it shows the stalked spore- 

 capsule burst into four valves; attached to the valves are the elaters. 3 a shoot of the same Frullania seen from the 

 under side ; at the base of each leaf is a little pitcher containing a Rotifer. The little toothed scales lying on the stem are 

 the amphigastria. ■» A single pitcher and its contained Rotifer. * The Rotifer (Callidina symhiotica) removed from the 

 pitcher. 1 nat. size ; 2 x 20 ; 3 x 25 ; * x 30 ; 5 x 100. 



— alone amongst the Liverworts — stomates occur upon the spore-capsule. It 

 dehisces into two valves. 



There are 103 species. 



Jungermanniacem. — Include both thalloid forms, in which the oophyte genera- 

 tion has a general resemblance to that of a Marchantia, and creeping leafy forms 

 (c/. fig. 896 ^) ; the latter are by far the more numerous. The sporogonium in both 

 cases consists of a long-stalked capsule which splits into four valves (fig. 396 ^). 

 Elaters are present, often attached to the capsule-wall. The Jungermanniaceae 

 grow for the most part on damp earth, stones, and bark of trees. 



The thalloid forms include the very common Pellia — like a Marchantia, with 



