Zbe ipdgdmg of tbe HJear 149 



abundance. They cover ragged rocks, dress up old 

 roofs, walls, fence-rails, and dead stumps, especially 

 delighting in the north side of trees. If we examine 

 them through a magnifying glass we shall see that 

 they are made up of cells, laid side and side like 

 little chains of beads, or of cells expanded into short 

 tubes or threads, l3"ing like heaps of tiny fagots. 

 Instead of seeds, lichens have a fine dust called 

 spores, from which they develop. 



Lichens are exceedingly long-lived and excessively 

 slow of growth. The lily attains its lovely maturity 

 in a few months ; the oaks, elms, pines, become great 

 trees in twenty or thirty years ; the humble lichen 

 often lives forty or fifty years before it is old enough 

 to complete its growth by producing spores. Bot- 

 anists say that the life of a lichen is fitful and strange, 

 and is practically indefinite as to duration. Lichens 

 simply live on and on. 



Some lichens have been known to live nearly fifty 

 years without seeming to grow ; the}^ appear to dry up, 

 and nearly vanish — then suddenly, from some cause, 

 there is a revival of growth, they expand again. Small 

 and insignificant as these lichens are, they often out- 

 live those longest-lived of trees, the cedar of Lebanon 

 and the California redwood. 



The condition of lichen existence is water, for from 

 moisture alone, in dew or rain, they secure their food. 



