13 ° 
F. E. Fritsch and E. J. Salisbury. 
We have noticed that in the first stages the Cystococcus appears 
as dark green granules in the depressions; on slightly older burnt 
areas ( e.g ., F 2, F 3) the dark colour of these granules gives place 
to a pale yellowish-green, due to the envelopment of such Cystococcus- 
groups by the colourless hyphae of an additional fungus, as an 
incipient stage in lichen-formation. Of the lichens that arise in 
this way on relatively young burnt areas Cladonia delicata Ehrh. is 
at first the only one to be found in fruit, but others in the sterile 
condition are probably associated with it. The small scale-like 
lobes of their pale green thalli form numerous patches on the soil 
and these are dominant for some years on the barer parts, until in 
fact the Phanerogamic vegetation begins to close, when they become 
subordinated to other forms or completely disappear. 
Simultaneously with the gradual development of the Lichen- 
flora we have an increase in the Glceocystis and its associates over 
the general surface, these, together with Mesotcenium violascens De 
Bary, forming increasingly conspicuous jelly-like lumps of a dirty 
green colour which occupy practically the whole surface left bare 
by other forms. 1 Such lumps are generally visible with a lens 
about two years after the occurrence of a fire and gradually increase 
in bulk, so that approximately three years later they are discernible 
on close observation to the naked eye. Finally, in the tall Calluna 
the gelatinous forms occur as conspicuous masses from a quarter 
to half an inch in diameter. It will be realised that, as regards the 
cryptogamic flora, the association is closed almost from the first. 
Apart from the forms already mentioned the only other algae 
encountered on the burnt surface are Hormidium flaccidum A. Br. 
and Zygntma (Zygogonium) ericetorum Hansg., both of which, and 
particularly the latter, are rare and local in their distribution. 2 
Some three or four years after a fire Cladonia delicata becomes 
associated with C.furcata Hoffm., C. Flcerkeana Fr. forma trachy- 
poda Myl., C. pyxidata Fr., C. squamosa Hoffm., and rarely 
C. sylvatica Nyl.; of these five C.furcata seems to be the first to 
appear. As the phanerogamic vegetation becomes more and more 
closed, C. sylvatica increases in amount and with it, in these later 
stages, are found C. pyxidata and C. coccifera Schaer. The lichens 
appear to reach their maximum development, both as regards 
amount and variety of species, in the phase which we have termed 
1 The absence of diatoms in the algal covering is noteworthy. 
2 Although examined at different times of the year there appears to be no 
seasonal difference in the constitution of the algal covering. 
