THE FERN BULLETIN 



41 



Japan. The theory is that in the process of evolution, 

 tile stock from which a modern fern came, might give 

 rise to exactly the same form in widely separated 

 regions if the physical conditions were the same. It 

 is as if our widely distributed bracken should produce 

 the same spot in both Hemispheres. It is well known 

 that our lady fern, ostrich fern, and royal fern pre- 

 sent certain small variations not seen in the European 

 plants and it has frequently been proposed to consider 

 them separate species. Those who believe the ferns 

 of the two regions to belong to one species, account 

 for their differences by differences in environment, or 

 else by this theory that the two have had a separate 

 origin. Considering all the surroundings, however, 

 it does not seem probable, that this theory will fit the 

 case of altcnians. If it were invoked to explain its 

 presence in Arizona the absence of the^fern from other 

 locations in the same region must also be explained. 



Last, and most likely of the theories advanced to ac- 

 count for the fern's occurrence, is that the colony has 

 arisen from wind-blown spores. This is, indeed, the 

 first explanation to come to mind in this and similar 

 cases, but while considering it, it is well to remember 

 that foi some reason ferns seldom spread into far off 

 regions in this manner. Within less than two hun- 

 dred miles of Florida, there are five hundred species 

 of ferns, and there are twice as many within a 

 thousand miles, yet they do not gain a foot hold in the 

 latter region although conditions there are seemingly 

 as favorable as anywhere else. In more northern 

 regions we do not find the adderstongue, the narrow- 

 leaved spleenwort, the fragrant fern or Golclie's fern 

 in every locality that is suitable, though their spores 

 have doubtless been showered upon such regions an- 

 nually for ages. In the case of A'splenium altcnians 



