90 Current Investigations in Economic Botany. 
Much more evidence might be called, but the above will 
probably be sufficient to prove that seedling canes have proved to 
be a factor of great economic importance in raising the sugar 
industry of the West Indies from the depressed condition into which 
it had fallen, due in considerable measure to the prevalence of 
fungoid disease which attacked the old standard varieties from about 
1894 onwards. 
The great expectations once held of seedling canes may not 
have been realized, and the evidence available indicates that perhaps 
about 25 per cent, is the maximum amount of sugar which sugar- 
canes will yield and be profitable. Increase of yield beyond this 
point must be sought rather by increasing the tonnage of the canes 
than by attempting to enhance their sucrose contents. 
Disease resistance may be only relative. It must be remembered 
that in the case of the older canes propagation by cuttings from canes 
permeated with fungal hyphae ensured the continuance of the disease 
as each cutting carried the disease within it and had not to wait for 
infection. With seedlings a new race was started free at first from 
disease but as this stock, like the former, is propagated year after 
year by cuttings the diseases will probably be propagated too, so 
that in the course of a few years another new race would be 
required to ensure a relatively disease free stock. 
The greatest hope for the future lies in the expectation that it 
may become increasingly practicable to raise canes of definitely 
known parentage from carefully selected plants possessing to the 
greatest degree the characteristics of disease resistance, high sucrose 
yield, heavy tonnage of cane and the other properties which have 
been previously mentioned as marking a sugar-cane of high 
economic value. 
