110 AMERICAN FERN JOURNAL 
Observations on the habitat of certain ferns 
EDGAR T. WHERRY 
In the course of geological field-work in the Appa- 
lachian Mountains the writer has often found ferns 
which are usually regarded as characteristic of caleareous 
rocks growing on rocks such as granite, sandstone, and 
schist, which are as a rule very low in lime. In order to 
ascertain whether the presence or absence of lime in a 
rock has anything to do with the growth of the ferns 
upon it, a series of chemical analyses has been made, 
with the results herein described.* 
For the first subject the walking fern, Camptosorus 
rhizophyllus, was selected, and samples of the rocks and 
the soils on which it was growing were collected at 
twenty stations in Pennsylvania, Maryland, Virginia, 
and West Virginia,? ten different rocks being repre 
sented. The percentage of lime in each rock was firs 
determined, and, as had been expected, was found te 
vary widely; one pure limestone proved to contain over 
53% of lime, but there was less than 5% in many of the 
rocks, and mere traces in several of them. The fern}; 
therefore. by no means limited to calcareous rocks; it 
must get lime from some source, however, for analysis 
of the ash obtained by burning its leaves showed the 
presence of 30% or more of this constituent. So examil- 
ation of the soil in which its roots were imbedded seemed 
desirable. 
‘The detailed results of the analyses so been apes in Jour 
aes, in 1G: Daaee 879-4 on 
Davis, . Bucknell University Lewis burg, Pa.; : 
: ir- 
ee Stotler and Prof. - T. McDonald, of Harper's Ferry, West V 
ie comprised limeston Anite Pane limestone-PeP>® 
conglomerate, hat gneiss 
sat = argillaceous lim: nacadihegr os ca-schist, granite, — 
essere, and quartzite; there were also two occurrences mie 
