Mosses and Lichens 



with here and there cells whose walls have remained thin and 

 yellowish. Immediately without the central portion is a 

 zone of several layers of thin-walled narrow cells, bounded 



dendroides. 



Mnium undidatum. Cross 



j,,/ , -,IVM,,Y,/,H jtnftirira Pr-nc<: (^lwlac^um dendrotdes. 

 Aulacommum pabistre. Lross section of stem to show cell 



nf rpntral mrt of <;tem CrOSS Section OI central _ 



structure without fibro-vascu- 

 lar bundles. 



part of stem. 



on the outside by from one to three layers of cells with 

 thin, mostly dark-brown, walls. These as well as the cells 



lying immediately within are char- 

 acterised by the starch contained in 

 them as are the narrow cells of the 

 leaf-traces. 



The "roots" are very simple in 

 structure, being either hair-like tubes 

 or simply chains of cells. To dis- 

 tinguish them from the roots of higher 

 commune. plants they are called rhizoids. 



Cross section of stem. 



ANTHERIDIA 



Antheridia, or the male organs of the Bryophytes, are spheri- 

 cal, oval, or club-shaped bodies, with long or short stalks. They 

 consist of an outer wall of a uniform layer of cells, and an interior 

 tissue formed of numerous small cells, in each one of which a 

 sperm-cell has its origin. (See diagram on page 40). 



The sperm-cell is a spirally coiled filament, thickened at the 

 rear and pointed at the forward end with two long fine cilia 

 projecting from the point. 



When mature, the antheridia walls rupture, and the sperm- 

 cells, in virtue of their coils, spring from the antheridia and by 

 means of their cilia swim in water to the archegonia. 



46 



