Inorganic Constituents of Lichens. 4$ 



quired for the growth, both of themselves and of a higher 

 order of plants. They may therefore be considered as pro- 

 ducers of manure, or as constituting foci of matter necessary 

 for the nourishment of plants. 



Where lichens can be procured in abundance, a circum- 

 stance which may occur frequently in reference to the rein- 

 deer lichen, so frequent on our moors, they may be used 

 with great advantage as manures, since they contain a larger 

 amount of inorganic matter than any other plants, with the 

 exception of the sea-weeds. The following Table contains my 

 analyses of three kinds of wood, Lima, Sapan and logwood, 

 from which it will be observed that the quantity of salts is 

 much inferior to that contained in many of the lichens : — 



Organic matter . . 

 Silica and sand . . 

 Common salt . . . 

 Phosphate and sul- 

 phate of soda . 

 Phosphate of lime . 

 Carbonate of lime . 



1000- 1000- 1000- 



The relative amount of inorganic matter in various classes 

 of plants is apparent from the following Table, where the com- 

 position of 1000 parts of each of the plants is exhibited: — 



Lima. Sapan. Liciiens. Algae. 



Organic matter . .971-25 987-08 932-5 762 

 Inorganic matter . 28-75 12-92 67-5 238 



In this table the composition of the yellow Parmelia has 

 been adopted, while in the algae the result of the analysis of a 

 gigantic sea-weed from Cape Horn, supplied me by Dr. Joseph 

 Hooker, has been introduced. 490 grains of this plant yielded 

 by incineration 116*7 of ashes, equivalent to 23'8 per cent. 



The introduction of inorganic matter into the substance of 

 trees and lichens can only be effected by the inferior extre- 

 mity and surface of those portions which are in contact with 

 the source of this peculiar pabulum of vegetable life, while it 

 would appear that the connexion which we always find to sub- 

 sist between sea-weeds and some fixed rocky position, even in 

 the case of these immense inhabitants of the southern seas, ac- 

 cording to some physiologists, only serves the purpose of re- 

 taining them stationary in one locality, their food l)eing derived 

 from the fluid in which they are immersed. But whether this 

 be true or not, it is certain that the waters of the ocean are 

 capable of affording all the inorganic constituents with which 



