ECONOMIC MYCOLOGY. 317 
ECONOMIC MYCOLOGY. 
By Professor M. C. Potter, Sc.D. 
[Being a Paper read in introducing the Discussion on Economic Mycology at the 
Meeting of the British Association (191 6).] 
In introducing a discussion upon the economic aspects of Mycology, 
I would begin by emphasizing the real importance of this branch of 
Botany to the nation, and the vital necessity of a study of the causes 
contributing to the enormous loss of food throughout the country 
and Empire. 
Let us consider for a moment the very large proportion of the 
world's commercial products which are entirely of vegetable origin. 
Such would include coal, timber, rubber, cotton, sugar, cereals and 
other grains, the fruits and vegetables, tea and coffee, cocoa, tobacco, 
&c, and when to many of these are added their innumerable uses 
in the arts and manufactures we are reminded how absolutely all 
life On the globe is dependent upon the chlorophyll corpuscle. Now, 
with the exception of coal, the plants producing the materials 
enumerated are all subject to the attacks of fungoid or bacterial 
parasites, and thus it is seen how essential it becomes that more and 
more attention should be directed to the study of plant pathology. 
The extent of the loss occasioned by diseases of a parasitic origin is 
perhaps hardly realized. Some slight indication of it may be given. 
With regard to wheat : for the British Empire "I am not aware that 
any monetary estimate has been attempted of the loss caused by 
rust " or other parasite, but it is certainly enormous ; and in Germany, 
where we may look for more scientific calculation of their resources, 
it is known that in the year 1891 the loss to the German Empire 
upon the cereal crop of wheat, barley, oats, and rye was over twenty 
millions sterling, an amount nearly equal to one-third of the total 
value of the crop. In Australia the loss due to rust of wheat has 
been estimated at two and a half millions for the year 1 890-1891. 
In Germany the loss due to disease of the potato crop amounted 
in one year to thirty millions, and in our own country it has been com- 
puted that this crop is reduced by disease by at least one-third on 
the average. This would represent over one million tons of potatos 
lost by disease per annum in England alone. In Ireland the potato crop 
suffered to the extent of six millions in 1879, and in 1845 practically 
the entire crop was destroyed through the ravages of Phytophthora 
injestans, producing a most disastrous famine throughout the country. 
In Northumberland and Durham, swedes and turnips are ex- 
tensively cultivated for feeding purposes, 50,000 acres being thus 
employed in these two counties alone. Plasmodiophora attack is 
