118 F. E. Fritsch and E. J. Salisbury. 
P 3. Burnt August, 1911 ; situated on both sides of valley A, 
on slopes and central ridge; aspects respectively W.N.W. 
and E.S.E. 
F 5. Burnt 1909 ; situated mainly on N.W. slope of valley A ; 
aspect E.S.E. 
F 7. Probably burnt in 1907, but exact date of fire unknown ; 
developed as CUE facies on lower slopes of “central 
ridge ” (shaded in map); aspects diverse. 
The subsequent matter is divided into the following sections:— 
A. The primary effects of burning (p. 118). (1) Destruction 
of the aerial organs (p. 118). (2) Killing of certain 
constituents of the vegetation (p. 119). (3) Destruction 
of the peat (p. 121). 
B. The effects of exposure (p. 122). (1) Evaporation-data 
(p. 122). (2) Wind-trimming (p. 125). (3) Growth-forms 
on the land-slides (p. 128). 
C. Colonisation (p. 129). (1) Cryptogamic succession 
(p. 129). (2) Phanerogamic succession (p. 132). 
We take this opportunity of expressing our indebtedness to the 
Local Committee of the National Trust, in charge of the Hindhead 
Common, for giving us facilities to carry on the work, and particu¬ 
larly to Mr. W. C. Marshall and Mr. H. B. Dempsey for useful local 
information. We have also to acknowledge a grant from the Council 
of the East London College in aid of expenses incurred in connec¬ 
tion with the work. 
A.— The Primary Effects of Burning. 
The first results of a heath-fire may be considered under three 
headings, viz., (1) the destruction of the aerial organs, (2) the killing 
of certain constituents of the vegetation, and (3) partial or complete 
incineration of the peat. 
(1) Destruction of the aerial organs. 
At the outset attention may be called to the eccentricities which 
heath-fires often exhibit. Small patches of the vegetation are 
frequently left untouched, whilst all around is burnt. The limits of 
a fire are also extremely arbitrary. The most striking case of this 
kind is that furnished by the fire which took place some seven years 
ago and which left the whole of the “ central ridge ” untouched 
(3, p. 153), the edge of the fire being now marked by a sudden drop 
in the level of the vegetation, as we pass from the unburnt (15 years 
