156 



POPULAll HISTORY OF LICHENS. 



and the tartrate and phosphate of lime. Its ash, according 

 to the analysis of Mr. Wallace Lindsay, contains the bases 

 lime, potash, soda, magnesia, and peroxide of iron, in com- 

 bination with sulphuric, hydrochloric, and phosphoric acids. 

 Its thecse are short, small, and closely crowded in the tha- 

 lamium ; the spores are minute, oval, simple, colourless, and 

 intermediate in size between those of Comicularia and 

 Cladonia. The spermogones are seated on the apices of the 

 rigid marginal cilia, whose function appears normally to bear 

 these organs, but which are frequently sterile. The sper- 

 mogones are solitary or grouped in twos or threes ; the 

 spermatia linear and straight. 



On the presence of a large amount of starch chiefly de- 

 pends the extensive use of this Lichen in northern coun- 

 tries as an article of food, and in medicine as a nutrient, 

 demulcent, and tonic. When boiled in water, it yields a 

 tolerably firm jelly, which however contains some of the 

 bitter principle of the plant, giving it not only a disagree- 

 able taste, but a purgative quality. This can be removed 

 by previously steeping the plant in a weak solution of carbo- 

 nate of potash or soda; and the jelly prepared from the Li- 

 chen thus purified, when mixed with wines, sugar, or spices, 

 or flavoured with various aromatic substances, is a very 



