SYMBIOSIS 293 



that the two constituents of the Lichen have come, as 

 it were, to an agreement as to the part which each 

 is to play. The Alga, by means of its green chlorophyll, 

 undertakes the manufacture of the food-supply, while 

 the Fungus looks after the reproduction of the species. 

 This extraordinary mutual benefit society of two quite 

 different plants — a condition which the botanist calls 

 symbiosis — is not confined to the Lichens, though they 

 form by far the largest group of symbiotic plants. 



