Experiments on the Growth of Fungi on Culture Media. 
BY 
WILLIAM BROWN, M.A., D.Sc. , 
(.From the Department of Plant Physiology and Pathology , Imperial College of Science and 
Technology , London .) 
4 
With seven Figures in the Text. 
T HE experiments to be described in the present paper had their origin 
in certain unexplained results which were met with in the course of an 
investigation of the growth of fungi in atmospheres of different composition . 1 
It was there found that the effect of moderate concentrations of carbon 
dioxide (10-20 per cent.) consisted in general in a reduction of growth as 
measured in terms of the diameter of the fungal colony. This result was 
obtained, for example, with cultures of Botrytis cinerea and Alternaria 
grossttlariae on a variety of media. Here the cultures in air were in 
advance of those in 10 per cent, carbon dioxide throughout the whole 
period of examination. On the other hand, certain clearly marked excep¬ 
tions to this rule came to light. Thus it was found that with cultures of 
Sphaeropsis malorum on certain media the colony growing in 10 per cent.' 
carbon dioxide at first lagged behind the one growing in air, but later on 
very distinctly surpassed it. It was with the view to a better understand¬ 
ing of such behaviour that the present study was undertaken. 
In the course of this study it was found that the method of experiment 
adopted (which consisted chiefly in the systematic measurement of the rate 
of spread of the fungal colony) appeared to offer a promising basis for 
physiological work on fungi, on which account the scope of the investigation 
has been considerably extended. Briefly expressed, the aim of the in¬ 
vestigation has developed into the study of the form of fungal cultures, chiefly 
in its relation to external factors. In how far this can be accomplished with 
the methods at present available, or how far these can be developed to meet 
the new problems that arise, only subsequent work can show. Since the com¬ 
pletion of the work of which the present paper is an account, considerable 
progress has been made in a number of directions, and the writer believes 
that it will be possible by work along these lines to attack two large 
1 Ann. Bot., xxxvi, p. 257, 1922. 
[Annals of Botany, Vol. XXXVII, No. CXLV, January, 1923.I 
