20 GUIDE TO THE STUDY OF LICHENS. 



tains a high percentage of lichenin. The peasantry of 

 Iceland, Norway and Sweden powder it and mix it 

 with the flour of various cereals and mashed potatoes, 

 from which an " uncommonly palatable and healthful 

 bread is prepared." A diet of this lichen was also 

 said to prevent a peculiar form of scurvy, or elephan- 

 tiasis, known as " Iceland scurvy," quite prevalent in 

 Iceland and the Scandinavian peninsula. 



Rock-tripe, a species of Umbilicaria, has often been 

 the means of saving the lives of arctic explorers, not- 

 ably the members of the Franklin expedition, also of 

 trappers and hunters in Canada and Alaska. Some 

 of the companions of Franklin found, to their sorrow, 

 that a diet of this lichen produced a severe intestinal 

 inflammation, no doubt due to the bitter principle it 

 contains. This bitter principle is more or less present 

 in all lichens, and is said to be removed by repeated 

 washings or soaking in a solution of potash or some 

 other alkali. In the northern countries of Europe a 

 common method of preparing lichens for the table was 

 to make a decoction in milk after they had been re- 

 peatedly washed in water. It is, however, very difl[i- 

 cult to remove the objectionable bitter principle entirely, 

 and for this reason lichens were never extensively used 

 as an article of diet, excepting in cases of famine. The 

 peasants of Norway and Sweden collect large quantities 

 of various lichens as fodder for their cattle. Every 

 one is familiar with reindeer-moss (^Gladonia rangi- 

 ferind) as a food-supply for the reindeer of Lapland. 



Perhaps the most important and oldest use to which 

 lichens had been put was in the dyeing industry. 



