66 Rhodora ' [Marcu 
plains south of them, under any imaginable conditions of climate, is 
quite as far beyond the range of possibility as to extend across the 
wide ocean." ! 
The fact that many plants are calcicolous, many calcifuge, is clearly 
recognized by the European ecologists, Tansley in his wonderfully 
lucid little book, Types of British Vegetation, saying with perfect posi- 
tiveness: "Soils containing a comparatively large proportion of lime 
are always marked by the presence and usually by the abundance of 
certain species of plants — the so-called ‘calcicole’ species... . Con- 
trasting with the ‘calcicole’ species there are others, called 'calcifuge' 
which appear to be really intolerant of much lime in the soil." ? 
Again, Praeger in his monumental Irish Topographical Botany says 
without quibble: “The presence or absence of lime is the most import- 
ant particular in which petrology affects the distribution of plants; 
and in Ireland the bold grouping of the calcareous and non-calcareous 
rocks helps to emphasize this feature of phytogeology. . . . A knob 
of Old Red Sandstone . . . breaking through the limestone crust of the 
Central Plain, immediately produces Galium saxatile, Vaccinium 
Myrtillus, Rumex Acetosella, Deschampsia flexuosa, and other char- 
acteristic calcifuge species. . . . The converse case — the absence of 
calcicole species in counties poor in or devoid of limestone — is more 
strongly marked. ...A... conspicuous line of demarkation — indeed 
one of the most remarkable phytogeological boundaries in Ireland — 
is seen where the Central Plain limestones lie up against the ancient 
metamorphic highlands of Connaught....Here, as we pass off the 
limestone, Habenaria intacta, Gentiana verna, Sesleria, and other 
interesting plants which have been our companions over many miles, 
give way abruptly.” ? 
Why is this almost axiomatic law blindly ignored or only grudgingly 
admitted by so many American physiographic ecologists and phyto- 
geographers? That it is fundamental is beyond dispute, and by the 
English, Irish, and many other European investigators is clearly 
recognized as an essential factor in phytogeography; and as someone 
has said, “If the English and Irish agree on it, it must be so.” Until 
American physiographic ecologists and phytogeographers recognize and 
use this law as a constant guide their labors, as Dawson prophetically 
said, “will be to a great extent fruitless.” 
1 J. W. Dawson, Can. Nat. and Geol. vii. 342 (1862), 
2 Tansley, Types of Brit. Veg. 144 (1911). 
3 Praeger, Irish Topogr. Bct.: Proc. Royal Irish Acad. vii. p. xxvii (1901). 
