The @rigin of our British Flora 
to-day, and worse than it was in the same district at-an 
earlier date, when birches grew in the same place. Such~ 
peat-mosses show a succession of deposits as follows :— 
Recent or Youngest 7. Peatmoss, Sphagnum. 
7. 
6. Pine forest or Upper Forest. 
5. Peat bog plants or Upper Peat bog. 
4. Arctic plants or 27d Arctic, Empetrum. 
3. Peat bog plants or Lower Peat. 
2. Birch or Lower Forest. 
I 
Oldest Deposit . Ist Arctic or Dryas flora.® 
From Mr. Clement Reid’s papers, and especially his 
“ Origins of the British Flora,” we know not only a large 
number of th nts which were found in Britain during 
the I ge, but also a large number of preglacial 
s 
Even at that distant date, chickweed, Polygonum 
persicaria, meadow-sweet and hawthorn were living in 
England. The alder and bogbean (Menyanthes) were 
not only preglacial but occurred in all the deposits down 
to those of Neolithic age. There are many signs of the 
warmer and milder character of the interglacial period 
which, as we have seen, is indicated even in Scotland. 
Trapa natans is now no longer British, though it 
grew near Cromer before the Ice Age. Indeed, what 
strikes one most from these lists is how little and 
not how much difference was caused by the great ice 
invasions. 
It is a very pleasant duty to recognise the extremely 
valuable nature of these discoveries, which have in- 
deed explained the past history of the British flora in 
a very satisfactory way. The British botany of to-day 
may indeed be proud of these researches, though 
there are of course many doubtful points as yet un- 
explained. 
Dr. Lewis has compared his results with Professor 
227 
