698 



THE SUBDIVISIONS OF THE VEGETABLE KINGDOM. 



AntJiocerotacece. — 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 



Fig. 396.— Jungernianniaceae. 



• 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. s 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 

 tlie araphigastria. * A single pitcher and its contained Rotifer « The Rotifer {Callidina symhiotica) removed from the 

 pitcher. 1 nat. size ; 2 x 20 ; s x 25 ; < x 30 ; s x 100. 



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

 dehisces into two valves. 



There are 103 species. 



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

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

 (cf. fig. 396 ^) ; 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 Jungermanniacese 

 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 



