31. 



idea among the students of the epiphytes has been 

 that light and humidity are the main conditions 

 that influence the distribution of these plsuits. 

 However, no experimental evidence has so far been 

 given in support of this view.' 



It is the aim of this paper to present the 

 results that were obtained from a series of experiments 

 carried on from July 1921 to July 1922 chiefly 

 on Q.uercu3 stellata which was thickly inhabited. 

 at certain heights and on certain exposures by the 

 epiphytic Polypodium polypodioides . The oak was 

 located in an open pasture with no buildings orlother 

 trees within a radius of three hundred feet or more,- 

 The epiphytic flora and the location of this particular 

 tree were described in detail above (station #6 ), 

 This oak was particularly desirable for the study 

 of the influence of the climatic conditions on the 

 distribution of the epiphytic polypody, for its isolated 

 position exposed it on all sides to the unmodified 

 natural climatic conditions.' 



Prior to the work on the oak, preliminary 

 experiments were also madaon a specimen of Jtmiperus 

 virginiana which was inhabited by the fern, On this 

 tree the polypody favored no definite exposure, The 

 location of the juniper and its epiphytic flora are 



