402 ECONOMIC AND TECHNICAL 



It is interesting to recall a discovery of prehistoric remains at the 

 Abbey of Schussenried on the Lake of Constance and described by F. Keller 1 : 

 under successive beds of peat and crumbly tufa, there was found a layer, 

 3 feet thick, containing flints, horns of reindeer and bones of various animals, 

 and, along with these, masses of reindeer moss ; a sufficient proof of its 

 antiquity as a fodder-plant. 



d. FOOD FOR MAN. Lichens contain no true starch nor cellulose, but the 

 lichenin present in the cell-walls of the hyphae has long been utilized as 

 a food substance. It is peculiarly abundant in Cetraria islandica (Fig. 128), 

 which grows in northern countries, covering great stretches of ground with 

 its upright strap-shaped branching fronds of varying shades of brown. In 

 more southern lands it is to be found on high hills or on upland moors, but 

 in much smaller quantities. Commercial " Iceland moss " is supplied from 

 Sweden, Norway or Iceland. In the last-named country the inhabitants 

 harvest the lichen preferably from bare stony soil where there is no admixture 

 of other vegetation. They revisit the locality at intervals of three years, the 

 time required for the lichen to grow to a profitable size ; and they select 

 the wet season for the ingathering of the plants as they are more easily 

 detached when they are wet. If the weather should be dry, they collect it 

 during the night. When gathered it is cleansed from foreign matter and 

 washed in water to remove as much as possible of the bitter principle. It 

 is then dried and reduced to powder. When required, the powder is put to 

 macerate in water for 24 hours, or it is soaked in a weak solution of soda 

 or of carbonate of potassium, by which means the bitter cetraric acid is 

 nearly all eliminated. When boiled 2 it yields a jelly which forms the basis 

 of various light and easily digested soups or of other delicacies prepared 

 by boiling in milk, which have been proved to be valuable for dyspeptics or 

 sufferers from chest diseases. The northern nations also make the powder 

 into bread, porridge or gruel. Johnson 3 states in his account of " Useful 

 Plants " that considerable quantities of Iceland moss were formerly em- 

 ployed in the manufacture of sea biscuit, and that ship's bread mixed with 

 it was said to be less liable to the attacks of weevil than when made from 

 wheat flour only. 



An examination of the real food value of the mucilaginous extract from 

 "Iceland moss" has been made by several workers. Church 4 states that for 

 one part of flesh formers, there are eight parts of heat-givers reckoned as 

 starch. Brown 8 isolated the two carbohydrates, lichenin and iso-lichenin. 

 The former, a jelly which yields on hydrolysis a large quantity of a reducing 

 sugar, dextrose, ferments with yeast and gives no phloroglucin reaction ; 

 it is unaffected by digestion and probably does not form glycogen. 



1 Keller 1866. 2 Proust 1906. 3 Johnson 1861. 



4 Church 1880. 5 Brown 1898. 



