Sor Reactions oF CERTAIN Ferns—I 15 
PawNEE county: Table Rock, May, 1896, J. E. 
Shue. . 
LANCASTER County: Lincoln, June 3, 1890, no. 6128, 
H. J. Webber, from Lucena Hardin; Lincoln, May, 1895, 
rich. moist woods, EZ. B. Robinson; another specimen by 
Fred C. Cooley without further data. 
University or Nepraska, LIncoun. 
(To be continued) 
Tke Soil Reactions of Certain Rock Ferns—I 
Epcar T. WHERRY 
Judging from the literature, the ferns which grow on 
rocks would appear to ‘be, on the whole, markedly sensi- 
tive to the chemical features of their soils. Their dis- 
tribution is of course controlled to some extent by phy- 
sical factors, such as climate, porosity of soil, availability 
of moisture, etc.; yet in many instances a given species 
has been eaaeess to grow in soils of widely varying 
physical character, but consistently associated with a 
particular type of rock, and accordingly more or less 
uniform in chemical composition. Again, soils of like 
physical properties but dissimilar chemical nature oftem 
occur in such proximity that spores of the various ferns: 
can not fail to have fallen into both kinds, yet flourish-- 
ing plants have developed in but one of them. 
It is commonly recognized that certain species of 
rock ferns grow by preference upon limestone and simi- 
lar rocks, and are accordingly to be classed as calcareous: 
soil plants. Other species, however, appear to avoid 
calcareous rocks quite definitely, and are presumably to 
be classed as acid soil plants. In the course of geological 
field trips and vacation outings for several years past 
the writer has been collecting information upon these 
