242 
Oscar Drude. 
Species. 
Germany. 
Great Britain. 
P. officinalis... 
On calcareous soils, 
quite absent from 
N.W. 
Through the whole 
of England to 
Scotland: no mar¬ 
ked soil preference. 
P. vulgaris (acaulis) 
Absent between the 
Alps and the north 
coast, though com¬ 
mon in France ... 
The commonest spe¬ 
cies throughout 
the British Isles. 
Cirsiutn oleraceum ... 
Common in alluvial 
meadows up to 
East Friesland ... 
Absent. 
C. anglicum (hritan- 
nicum )=C.pratense 
Rare in East Fries¬ 
land : otherwise 
absent ... 
Occurs in 49 English 
and 40 Irish coun¬ 
ties : local. 
C. heterophyllum 
On siliceous soils. 
Montane up to 
Thuringia, Baltic 
region. 
On siliceous and 
calcareous soils from 
Glamorgan to nor¬ 
thern Scotland. 
This list might be very greatly extended, but it suffices to 
indicate the material available for the developmental study of the 
flora. 
Although for the sake of contrast a few West European species, 
such as Corydalis claviculata, have been introduced into these lists, 
yet it may safely be stated that the great bulk of the species 
common to Great Britain and Central Germany consists of species 
with a wide montane distribution in Central Europe , often extending 
towards the east or into the Alpine countries. The lists may help 
to give an idea how apparently capriciously Great Britain has made 
her selection of these species. The question is worth some discussion, 
because certain important factors in distribution, which have not 
yet received attention, are involved. 
Origin of the British Flora. 
At the meeting of the British Association at Portsmouth (where 
we were handsomely entertained as guests of the Mayor at the 
conclusion of our journey) we had the pleasure of joining in the 
stimulating discussions of the Botanical Section. Clement Reid, 
in a paper read before this Section, developed with much acuteness 
an argument in which he answered the question of the origin of the 
British and Irish flora by supposing that the arctic-glacial element 
of the flora present after melting of the ice was enriched from the 
