76 ROMANCE OF LOW LIFE AMONGST PLANTS. 



were not autonomous plants, but mere compounds of 

 fungus and algas. 



This contention was opposed on the following 

 grounds : and, firstly, that the so-called fungoid 

 element was not a fungus, because lichens are peren- 

 nial ; they grow very slowly, but they attain an 

 extreme age. Some species, growing on primitive 

 rocks of the highest mountains in the world, are 

 estimated to have attained an age of at least a thou- 

 sand years ; and one author mentions, after the lapse 

 of half a century, having observed the same specimen 

 of Sticta on the same spot of the same tree. On the 

 other hand, fungi are mostly annual, very short-lived, 

 their whole existence being limited to a few weeks, 

 rapid in growth, and rapid in decay, not a trace of 

 some species remaining after a few days. 



Lichens will exist under conditions of aridity which 

 no other vegetables could support. Some are peculiar 

 to calcareous rocks, a few on arenaceous rocks, many 

 are common on the granitoid series, and one, Lccidca, 

 is frequent on the purest and smoothest quartz. 

 Fungi, on the contrary, must have moisture for their 

 very existence' sake, are mostly found in damp and 

 shaded situations, and could never exist under the 

 conditions above enumerated for lichens. Of all 

 plants lichens support extreme cold most success- 

 fully, whilst fungi succumb at the approach of frost. 



Lichens which grow upon the bark of trees may 

 be seen flourishing in profusion during the life and 

 vigour of the tree. Cinchona bark which has been 

 covered with lichens during growth has its qualities 

 improved, whereas the portions attacked by fungi 



