A Study of the Growth in Culture of Verticillium 
albo-atrum, B. et Br. 
BY 
H. CHAUDHURI, Ph.D. 
(.From the Department of Plant Physiology and Pathology, Imperial College of Science and 
Technology, London.) 
With twelve Figures in the Text. 
T HIS paper deals with the growth of Verticillium albo-atrum , B. et Br., 
with special reference to the effect of temperature and aeration. 
A comparison is also made of the method of estimating growth by surface 
spread of the fungus on a solid medium with a method of dry-weight deter¬ 
mination. 
The later portion of the paper deals with zone formation, and an 
attempt has been made to determine some of the conditions which bring 
about such formation. 
The original culture of V. albo-atrum was received from Dr. Bewley of 
Lea Valley Experiment Station, where it is a cause of wilt in tomatoes. 
In most of the experiments described, the fungus has been grown in 
Coon’s (1) medium ; so the effect of this medium in various dilutions and of 
its chief constituents on the growth of the fungus was first studied. The 
fungus also grows well in oat broth, oatmeal agar, wheat broth, prune juice 
agar, tomato-extract agar, potato-extract agar, and potato-mush agar. It 
grew in Dox’s or Czapek’s solution, and also in Richard’s synthetic solution. 
With solid media, agar was added in a concentration of 1J-2 per cent., 
according to the acidity of the solution; with prune juice 3 per cent, agar 
was found necessary to ensure setting of the medium. 
Very luxuriant growth takes place in potato mush and potato extract, 
and also on cooked banana and oatmeal agar. In Dox’s solution and in 
corn-meal agar, it grew rather indifferently. 
The sizes of the conidia varied with different media and with the liquid 
or solid nature of the medium. Sometimes the conidia, on germination in 
the hanging drops of water, produced abundant small secondary conidia ; 
the average size of these was 4-5 /x x 2-5 /x, while that of ordinary conidia was 
6-8 M x 2-5—5 M- 
[Annals of Botany, Vol. XXXVII. No. CXLVII. July, 1923.] 
