1888.] 
Dr A. B. Griffiths on Fungoid Disease. 
407 
directly through the reproductive system. In all cases there are two 
factors, the nature of the organism, which is much the most important 
of the two, and the nature of the conditions Whatever the 
cause may be of each slight difference between the offspring and 
their parents, — and a cause for each must exist, — we have reason to 
believe that it is the steady accumulation of beneficial differences 
which has given rise to all the more important modifications of 
structure in relation to the habits of each species.'^' These quotations 
from the master mind explain the complete absence in Ustilago 
cucumis of any true resisting-spores similar to those found in other 
species of the Ustilaginese. 
The spores of the cucumher-root fungus are found in the soils 
(where Cucumis saliva has been growing) in the autumn and early 
winter, having been liberated by the rotting of the root-nodules. 
These spores retain their vitality for months,* and are then capable 
of attacking the new seedlings planted in such soils. The spores 
are easily disseminated by such agencies as air, soils, and streams. 
The Groiotli of the Cucumber-Root Fungus in Culture Fluids. 
Ustilago cucumis is capable of growing in a nutrient culture 
solution such as that used by Professor J. von Sachs. Concerning 
this point the following experiments were performed : — 
A large number of seedlings were raised in good garden soil 
placed in small pots under a series of bell-glasses (fig. 6). The 
atmosphere within the bell-glasses was kept moist and at a summer's 
heat. Before the cucumber seeds were placed in the soil, they were 
steeped in an aqueous solution of ferrous sulphate (J^ per cent, 
solution) ;t by this means any spores of the root-fungus are com- 
pletely destroyed. The soil in each pot was “ watered ” with the 
same solution before the seeds were placed in it. After growing in 
the soil for a month the seedlings were transferred to the culture 
solutions. The culture fluid used was almost similar in composition 
to the one employed by Sachs ( Vorlesungen iiber Pflanzenphysiologie, 
p. 342), and consists of the following ingredients : — 
* See later on in this paper. 
+ See Dr Griffiths’ papers in Chemical News, vol. liii. p. 255, vol. 1. p. 193, 
vol. Iv. p. 276, vol. Ivi. p. 84 ; Chemiker Zeitung, No. 47 ; Journal Chemical 
Society, 1886, p. 114. 
