THALLOPHYTES : FUNGI 
295 
plant. In other words, a Lichen is not an individual, but a 
firm of two individuals very unlike each other. This habit 
FIG. 270. A common lichen (Physcia) growing on bark, showing the spreading thallus 
and the numerous dark disks (apothecia) bearing the asci. GOLDBERGER. 
of living together has been called symbiosis, and the indi- 
viduals entering into this relation are called symUonts. 
FIG. 271. A common foliose lichen (Pai^melid) growing upon a board, and showing 
apothecia. GOLDBERGER. 
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