116 EXPLOITATION OF PLANTS 
So there are voices even now which advocate a return to 
the austerity of vegetable colours and bewail the garish 
profusion of the coal-tar products. But they forget 
that time can only move forwards; the shadow may 
return on the dial perhaps, but it never moves back- 
wards. If vegetable dyes have really a part to play 
in the future, those who exploit them must go ahead 
and keep abreast of the chemical activity of the times. 
Certainly vegetable dyes can never hope to compete 
in variety of colour and tone with the hundreds of 
synthetic dyes, whose numbers increase every year. 
Why, even a simple colour like green had to be obtained 
by compounding yellow and blue, before the coal- 
tar greens were invented. But it is possible that, for 
certain standard colours for which there is a steady 
demand, and especially where fastness is important, 
a vegetable crop may be the most effective source of 
supply. This would apply most to the colours possess- 
ing heavier radicles—dark browns, blues, purples and 
blacks, whose synthesis is always a complex process, 
To compete successfully with coal-tar colours the 
highest efficiency must be maintained. If possible the 
dye principle should be extracted and sold in convenient 
form; the bulky dyeing woods, etc., are at a disadvan- 
tage in every stage of packing and transport, and 
ultimately in the dyeing trough itself. Further, if plant 
dyes are to be the standard fast colours in certain shades, 
the public should know their names so that, as in the 
case of indigo blue, any one can obtain a dye of proved 
quality by asking for, e.g., logwood black or cutch 
brown. 
Another and far more fundamental necessity is an 
