A GREEN LEAF 



79 



atmosphere. But how do the leaves take in this 

 gas? If we carefully examine the skin-tissue of 

 plants, especially the underside of the leaves, we 

 find intermixed with the cells numerous little 



i'ig. 51. Some breathing-pores of a monkey puzzle leaf 



mouths or pores, arrano-ed sometimes in rows, as 

 in Fig. ^ij which represents a portion of the 

 epidermis of one of the leaves of the araucaria, 

 or "monkey puzzle." These tiny mouths open 

 into the intercellular spaces in the spongy tissue, 

 and sometimes between the palisade cells, ot the 

 leaf The section of the pine-leaf which was shown 

 in Fig. ^S was cut through these tiny mouths or 



