a Yellow Colouring Matter. 191 



soda, and consisted of phosphates of iron, alumina, and lime. 

 The latter precipitates being tested with lead, yielded a pre- 

 cipitate of phosphate of lead, soluble in nitric acid. The 

 results of the analysis of two specimens of ashes were as fol- 

 lows : — 



Silica, 



Soluble salts, sulphate, phosphate, and 



muriate of soda, 

 Peroxide of iron, and phosphates of iron 



and lime, 



Phosphate of alumina. 

 Carbonate of lime, 



100. 100.0 



From these facts it is evident that this lichen requires the 

 same inorganic constituents for food as other plants, with this 

 difference, that the amount of inorganic substances present in 

 its composition is greater than in higher orders of plants, but 

 in a proportion tending towards that existing in the sea -weeds ; 

 another character, therefore, in addition to the general exter- 

 nal features, indicating an alliance between the algae and 

 lichens. '„ 



To ascertain if the great abundance of inorganic matter 

 was peculiar to this species, the Parmelia ofuphalodes was inci- 

 nerated, the specimen being taken from a portion collected by 

 a Highlander on the borders of Loch Venachar, where it is 

 extensely used, as well as generally in the Highlands, with an 

 alum mordant, to impart a fine purple to woollen cloths. Its 

 habitat had been a rock, and portions were selected free from 

 any appearance of suspended earthy particles among their 

 roots ; 200 grains gave a residue of 7.8 grains, consisting of 

 substances similar to those already enumerated in the analysis 

 of the yellow parmelia. Part of these, however, may have 

 been foreign. When we compare the amount of these inor- 

 ganic constituents with those found in trees, the balance ap- 

 pears in favour of the lichens, as shewn by the analyses of the 



* Mr David Murdoch assisted me in the first analysis, and Mr James 

 Murdoch in the second. 



