172 PAST AND PRESENT 
a reduced Continental one, many considerations, geo- 
graphical, climatic, and edaphic, must be duly taken 
into consideration if we are to understand the com- 
position and distribution of our vegetation. 
But making all allowance for these various disturb- 
ing influences, there are found in our flora certain 
plant groups which will not fit in with this general 
conception of immigration from the east. Let us 
take a few examples. In fir woods in Dorset, until 
some forty years ago (when it was exterminated), 
grew a Slender little plant allied to the Lilies, too little 
known to have a popular English name, and called 
by botanists Simethis planifolia or S. bicolor, the 
latter name having reference to the fact that the 
flower is purple on the outside, white on the inside. 
This plant is unknown elsewhere in Great Britain, 
and was at first set down by H. C. Watson, the lead- 
ing British plant geographer, as an alien or denizen, 
not a true native; but the fact that it grows over a 
considerable area of very wild ground in Kerry (its 
only Irish station), far from possible sources of intro- 
duction, and undoubtedly native, indicates a strong 
probability of the plant’s having been indigenous in 
Dorset also. It is not present on the adjoining parts 
of the Continent, but turns up again in the Pyrenean 
region, some 500 miles to the southward, and may be 
traced thence into Italy and North Africa. Did this 
instance of an apparent migration from the south 
stand alone, it might not excite much attention, and 
we should probably be inclined to attribute the plant’s 
peculiar and discontinuous distribution tothe extinction, 
perhaps by human agency, of intermediate stations. 
But it stands by no means alone, In Cornwall two 
