HUMBLE FAMILIES IN GRAY. 1 75 



disposition of many little germinating cells, called 

 gonidia, which are filled with a chlorophyll-like 

 coloring matter, and so minute that it requires a 

 powerful microscope to distinguish them. These 

 bodies, which are pushed through the closely- 

 woven threads of the upper bark layer, give it its 

 color. 



It would be interesting to further read the 

 inscription, the curious letters and figures, on this 

 antique rock sampler. When did the lichen artist 

 begin to weave her threads here ? She works 

 slowly on such looms, and in seasons of drought 

 lays by her shuttles altogether. Persons who 

 have had the curiosity to watch the progress of 

 certain specimens of the Parme/m^ for a quarter 

 of a century, say that they have remained in about 

 the same condition as when they first attracted 

 their attention. So this fohaceous web, that has 

 attained quite large dimensions, perchance could 

 have been seen by a wandering Natick, or had its 

 disk rubbed by the soft nose of the wild deer ! 



There is a singular genus of lichens, the com- 

 mon Cladonia,2 several species of which assume 

 peculiar, eccentric forms. The stalk-like eleva- 

 tions, called podetia, bearing fruit of various col- 

 ors, and rising from a mat of scale-like, half-erect 

 scalloped leaves of the thallus, which grows close 



1 " A small, round shield." 

 2 " A tender branch." 



