William Brown . 
i 16 
phenomena, not as yet fully investigated, have been determined ; 
others again which merely serve at present as starting points for 
further work. It has been thought advisable therefore to publish 
the following account, which aims at being a resume of the features 
already elicited, both published and unpublished, together with a 
general forecast of the lines which further investigation of the subject 
maybe expected to follow. The present somewhat informal publica¬ 
tion has the personal advantage of affording the writer an opportunity 
to express certain views which appear to him plausible in the light of 
present knowledge but which may require to be modified as know¬ 
ledge of the subject extends. It is hoped that it will also enable 
the general botanical reader to form a more connected picture of 
the idea and progress of the investigation than may be obtained from 
the detailed narratives which have appeared and are appearing from 
time to time elsewhere. 
Botrytis cinerea , the fungus which has formed the chief object 
of study, is a member of that large group of parasitic fungi which 
are characterised by the fact that they kill the tissue of the host 
plant in advance of their growth. This species was selected for 
the present work on account of its ubiquity, the readiness with 
which it reproduces itself, the rapidity and certainty with which its 
spores germinate, and the strongly marked features of its parasitic 
attack. This species is of further interest in that the majority of 
investigations dealing with the subject have centred round it or its 
near allies. 
It is not proposed to deal in detail with the statements in the 
literature bearing on this question. 1 Beyond the generally attested 
fact that such fungi kill in advance of their growth, much of the 
experimental evidence is of a highly unsatisfactory nature, and the 
statements put forward by various writers are in many cases 
contradictory. The primary object of the research was to aim at 
deciding on certain of these controversial points, and in the first 
instance to examine the nature of the principle of the fungus which 
is responsible for the phenomenon of “ action in advance.” This 
phenomenon has been known since the time of de Bary (1) to consist 
essentially of two processes, (a) the solution of the cell wall or at 
least of certain of its constituents so that the tissue loses its 
coherence, (b) the killing of the living protoplasmic contents them¬ 
selves. De Bary believed the phenomenon to be due chiefly to 
the action of an enzyme, but considered that certain salts (oxalates) 
1 For a detailed criticism, see No. I of the series already cited. 
