1909.] PUBLIC DOCUMENT — No. 31. 39 



are undoubtedly the principal factors responsible for this class 

 becoming more common than formerly, and the changed condi- 

 tions of the soil, brought about by the constant deforestation 

 and cultivation, which have been the means of changing the 

 humus and water-retaining capacity of the soil, are also respon- 

 sible for the present distribution of many of our plants. 



