45. 



is an indirect one, Its direct effect is really on 

 the evaporating pov/er of the air rather than on the 

 distribution of the pla^s on the tree. The arrangement 

 of the epiphytes according to the relative humidity of 

 tha air (Fig, 17) also suggests an indirect effect on the 

 regional distribution of the epiphytes on the tree. 

 Here, it appears, that where the humidity is the greatest 

 the hepatics occur; where it is the lowest the lici^ns 

 prevail. Apparently, the effect of the relative humidity 



of the air on the occurrence of the mosses ad the 

 polypody is not a very marked one since both of these 

 plants are found where the humidity is low as well as 

 where it is relatively high.Hovrever, neither the air 

 temperature nor the relative humidity of the air 

 present any marked variation on the different stations 

 on the tree, The curve of each is practically a straight 

 line while the light and the evaporation curves are 

 distinctly ascending curves indicating that the intensity 

 of these was quite marked at each station on the tree. 

 The substratum temperature curve (Fig, 18) does not seem 

 to show any definite relation to the occurrence oflthe 

 epiphytes on the tree. 



It is safe to conclude from the results obtsdned 

 that neither the light, the realtive humidity of the 

 air, the temperature of the air, nor the temperature of 

 the substratum exert any direct influence on the 



