55. 



their supporting plant has interested botanists for 

 a long time. The early workers, in fact, attri^ted 

 the occurrence of epiphytes in some places and their 

 ahsence in others chiefly to differences in light and 

 atmospheric humidity, To quote Schimper p. 90 (25), 

 "Licht, feuchte Luft.reichliche ThaulDildung,ha«fige 

 Regenguesse stellen die wessentlichen Bedingungen eines 

 ufeppigen epiphytischen Pflanzenlebens dar,"It was 

 Byer (2), however, who suggested that "only such plants 

 can live as epiphtes. .. .which can stand the hot sun and 

 the drying winds," In other words, he suspected that the 

 water supply and water loss is the most important problem 

 of the epiphyte. His suggestion indicates that only those 

 plants can exist as epiphytes which are capable of 

 resisting excessive evaporation. 



That the evaporating power of the air is actually 

 8J1 important factor in the occurrence and distribution 

 of the epiphytes is evident in the case of P.uolvioodioides 

 The graphical representation of the results obtained 

 (Fig, 14) as tabulated in Table III shows clearly that 

 it is the evaporating curve alone which bears a definite 

 relation with the distribution of the epiphytes. Thus, 

 where the evaporating power of the air is low the 

 hepatiOB, the mosses and the polypody occur; where the 

 evaporation rate becomes high, the hepatics begin 

 to disappear, while the mosses and the fern still persist; 

 as the rate of evaporation increases thejfern disappears 



