166 FIRST FORMS OF VEGETATION. 
lichens formed the principal drugs in the pharma- 
copeeia, and were prescribed for almost all the ills 
that flesh is heir to. Superstition had much to 
do with their popularity in this respect. Their 
strange shapes, their anomalous character, occupy- 
ing, as it were, an intermediate position between 
plants and minerals, between life and death; 
leading a perpetual mesmerized or suspended 
existence ; the curious situations in which they 
were found, growing on decaying wood or moist 
earth, or on the bare rock in weird, lonely spots, 
where fairies might sport and enchanters weave 
their unhallowed spells; they were naturally 
enough supposed by a credulous and ignorant 
people to be invested with magic qualities. As 
the knowledge of plants became more generally 
diffused, they lost much of their mystery, and 
consequently of their power over disease; and 
now they have almost entirely disappeared from 
medical practice. It must not be supposed, how- 
ever, that they were thus summarily expelled 
from the schools of medicine because they were 
entirely destitute of healing qualities. Some of 
them have been found, by chemical analysis, to 
contain principles of great efficacy in certain com- 
plaints; but as these principles varied in their 
strength, according to the circumstances in which 
the plants were produced, no dependence could be 
