no INTRODUCTION TO THE STUDY OF FUNGI 



Other vegetables could support. Some are peculiar to cal- 

 careous rocks ; a few are found on arenaceous rocks ; many are 

 common on the granitoid series, including micaceous, gneissic, 

 granitic, and quartzose rocks ; and Lecidea geoyra'phka is 

 frequent on the smoothest and purest quartz. Fungi, on the 

 contrary, must have moisture for their very existence, are 

 mostly found in damp and shaded situations, and could never 

 exist under the conditions just 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 ; 

 whilst Fungi do not and cannot flourish on growing and 

 vigorous bark, but on diseased, dead, or decaying spots. 



Lichens obtain the greater portion of their pabulum from 

 the atmosphere, and only their mineral constituents from the 

 matrix. Fungi, on the other hand, obtain their chief support 

 from the decaying vegetable matter on which they flourish, 

 gathering up a large store of the nitrogenous results of putre- 

 faction and decay, and disintegrating the matrix on which 

 they prey. 



Lichens in their chemical composition contain a large 

 number of substances which are wholly unknown amongst 

 Fungi, whereas also the most active alkaloids discovered in 

 Fungi have no analogue in Lichens, notably those of an active 

 poisonous character. 



Lichens contain but a small percentage of water as com- 

 pared with Fungi, so that in desiccation they do not shrivel, 

 collapse, or perceptibly diminish in . size ; whereas Fungi 

 shrivel up and collapse, so as scarcely to be recognised, become 

 liable constantly to the attack of insects, or, if damp, subject 

 to the development of mould ; whilst Lichens may be pre- 

 served for years under like conditions, without fear of insect 

 or mould. 



Lichens, when collected and cast aside without the 

 slightest care or precaution, do not exhibit the least tendency 

 to putrefy ; whilst Fungi, with the utmost care in drying, can 

 scarce be preserved from unmistakable evidences of incipient 

 putrefaction. 



