LICHENS AS FOOD 405 



20 cm. with irregular contorted lumps varying in size from a pea to a small 

 nut (Fig. 130). Externally these are clear brown or whitish; the interior 

 is white, and consists of branching interlaced 

 hyphae, with masses of calcium oxalate crystals, 

 averaging about 60 per cent, or more of the 

 whole substance. 



A still more exhaustive account is given by 

 Visiani 1 , who quotes the experience of a certain Fig . , 30 . Lecanora esculenta 

 General Jussuf, who had tested its value in the Eversm. Loose nodules of the 

 Sahara as food for his soldiers. When bread 



was made from the lichen alone it was friable and without consistency ; when 

 mixed with a tenth portion of meal it was similar to the soldiers' ordinary 

 bread, and had something of the same taste. The General also gave it as 

 fodder to the horses, some of them being nourished with the lichen and 

 a mixture of barley for three weeks without showing .any ill effects. It is 

 also said that camels, gazelles and other quadrupeds eat it with advantage, 

 though it is in any case a very defective food. 



A remarkable deposit of the lichen occurred in recent times in Mesopo- 

 tamia during a violent storm of hail. After the hail had melted, the ground 

 was seen to be covered, and specimens were sent to Errera 2 for examination. 

 He identified it as Lecanora esculenta. In his opinion two kinds of manna 

 are alluded to in the Bible : in one case (Exodus xvi.) it is the sweet gum 

 exuded from the tamarisk that is described; the other kind (Numbers xi.), 

 he thinks, plainly refers to the lichen. He considers that its nutritive value 

 must be very low, and it can only be valued as food in times of famine. 



B. LICHENS AS MEDICINE 



a. ANCIENT REMEDIES. An interesting note has been published by 

 Miiller-Argau 3 which seems to trace back the medicinal use of lichens to 

 a very remote age. He tells us that Dr Schweinfurth, the distinguished 

 traveller, who made a journey through the valley of the Nile in 1864, sent 

 to him from Cairo a piece of lichen thallus found in a vase along with berries 

 of Juniperus excelsa and of Sapindus, with some other undetermined seeds. 

 The vase dated from the i8th Dynasty (1700 to 1600 B.C.), and the plants 

 contained in it must thus have lain undisturbed over 3000 years. The broken 

 pieces of the lichen thallus were fairly well preserved; they were extremely 

 soft and yellowish-white and almost entirely decorticate, but on the under 

 surfaces there remained a few black patches, which, on microscopical 

 examination, enabled Muller to identify them as scraps of Everniafurfuracea. 

 This lichen does not grow in Egypt, but it is still sold there along with 



1 Visiani 1867. * Errera 1893. 3 Miiller-Argau 1881, p. 526. 



