NOVEMBER 255 



inches thick, over vast tracts of arid steppe in Tartary 

 and Asia Minor, and has often served to preserve life in 

 man and beast when more ambitious crops have failed. 

 From the reindeer moss (Gladina rangiferina), the chief 

 sustenance of those great deer in winter, the Russian 

 peasant has even learned to distil an ardent spirit. 



Lichens — some of them, at least — possess one quaUty 

 which, while it appeals powerfully to the imagination, 

 tends to deter all but the most patient from attempting 

 their systematic study. That quality is their immense 

 longevity and the exceeding slowness of their fructifica- 

 tion. Human life dwindles to insignificance before that 

 of a patch of stone lichen. The oak may live down 

 fifteen or twenty generations of men, and complete each 

 season its cycle of bud, flower, fruit, and fall ; but nothing 

 bides its time like the lichen. It may live down fifteen 

 or twenty generations of oaks. Mr. Crombie cites the 

 instance of a patch of Physcia parietina growing on a 

 granite wall. After five-and-forty years all the progress 

 he has been able to record is that 'the thallus is now 

 well developed, but no fructification whatever is visible.' 

 In fact, given no violent cosmic or permanent atmo- 

 spheric change, some lichens appear to be capable of 

 immortality, containing in their structure no occasion 

 of death. Lecidea geographica, the species which spreads 

 those beautifiil silvery stains in slowly broadening circles 

 upon the rocks, must be known to everybody. It is found 

 on the highest mountains in the world, wherever there 

 is a surface clear of ice and snow, and some of its patches 

 probably date from a time before man had come to claim 

 the lordship of creation. 



Curiously enough, within three miles of where I am 



