196 



AMERICAN HONEY PLANTS 



When evaporation is slight, as in a saturated atmosphere, water exudes 

 at the surface through pores such as occurs at the tip of a young grass or 

 clover leaf. Water pores of this sort are common. They are regarded as 

 pressure-valves by many botanists. The water that they eliminate is usu- 

 ally filtered by the protoplasm that it passes through, which does not allow 

 the passage of substances dissolved in the cell sap; but some plants which 

 grow where they absorb very "hard" water pass lime salts out through 

 their water pores to such an extent that they are encrusted with lime as 

 the water evaporates. 



irt of flo 



of Gc 



C opi 



froti 



m. (n) nectaries; (et) stamens 

 Bonnier's "Les Nectaires." 



Greatly magnified. 



The safety-valve elimination of water under strong internal pressure 

 and lessened normal evaporation is hardly to be called excretion or ac- 

 cretion; the extruded water is neither by-product nor manufactured out- 

 put. The elimination of lime appears to be on the border line of excretion. 



Nectar is not merely water; if it were its production would be more 

 easily understood. To the taste, it is sweet; to the sense of smell, it is 



