SYMBIOSIS 73 



existed a genuine bio-economic compatibility to render the 

 association possible, that a previous integrity on the part of 

 both partners smoothed the way for the union. We also learn 

 that in the domestic arts many lichens have been highly 

 esteemed as food and as medicine. They are of great 

 importance as supplying food for man and beast, containing 

 as they do starchy substances, and in some cases a small 

 quantity of saccharine matter of the nature of mannite. In 

 Lapland and other northerly countries they supply the winter 

 food of the reindeer and other animals. 



But the most singular esculent lichen of all is the " manna lichen " 

 which, in times of drought and famine, has served as food for great 

 numbers of men and cattle in arid steppes of various countries stretching 

 from Algiers to Tartary. This is derived principally from Lecanora 

 esculenta, which grows unattached on the ground in layers of 3-6in. thick 

 over large tracts of country in the form of small irregular lumps of a 

 greyish or white colour. 



The emancipation of the children of Israel from Egyptian 

 slavery necessitated at the same time emancipation from the 

 flesh pots of Egypt if the race was to be rejuvenated. The role 

 which manna whatever its origin played in this rejuvena- 

 tion must have been immense. " And the children of Israel 

 did eat manna forty years." It matters little for physiological 

 purposes whether this manna was provided by a lichen or by 

 some other strenuous vegetable organism. Like the eating of 

 unleavened bread, it was a "change of diet," calculated to 

 spell physiological emancipation from bad habits, and in its 

 physiological significance it is comparable to the "change of 

 diet" by Convoluta and rose-aphis when it flies off from cultiva- 

 tion into the fields. Nor was the lesson from the wilderness in 

 vain. Throughout the succeeding centuries the Jewish people 

 have provided martyrs not only for purely theological reasons 

 but also in the cause of Mosaic dietary legislation. Huxley 

 says : 



All that is best in the ethics of the modern world in so far as it 

 has not grown out of Greek thought or Barbarian manhood, is the direct 

 development of the ethics of old Israel. There is no code of legislation, 



