174 HUMBLE FAMILIES IN GRAY. 



an ash-colored rosette, so closely adherent to the 

 rock that it is impossible to remove it without 

 injury. It is curiously stamped with numerous 

 dimples or little shallow hollows, and the borders 

 are deeply divided into many long, narrow pin- 

 nately cleft lobes. Surely it is a pattern which 

 Flora with her looms and coarse needles devised 

 long ago. Indeed it is a kind of patchwork figur- 

 ing which must be cleaved from its substrate and 

 torn apart in order to examine the nature of the 

 fabric and the dye-stuff which stains it. The dis- 

 tinct, well-defined, bright white line along the rag- 

 ged edge of a scrap of it, catches the eye at once. 

 If it is viewed with a strong magnifier, it has the 

 appearance of the frayed borders of a thick piece 

 of white paper, with the alternate thread-like tis- 

 sues well woven together, and the broken ends 

 projecting in every direction. This is the pith or 

 marrow of the thallus ; the layer of starchy fila- 

 ments, stored for the life and support of the plant. 

 The thin, under bark layer is black, varnished and 

 bristling with numerous fibers. As many as 

 thirty are counted on a bit not larger than a 

 large pin-head, so there must be on this single 

 patch no less than thirty thousand of those 

 attaching threads, which so admirably serve to 

 keep it in its place. That part of the central 

 layer immediately beneath the upper crust or bark 

 is stained with light bluish gray, owing to the 



