48 Proceedings 
Let us consider now examples from these two classes of fungus 
diseases. 
As an instance of the introduction of a fungus disease the 
Powdery Mildew of the Vine ( Uncinula necator) may be taken. 
The first appearance of this mildew in Europe was notified in 
1845, on hot-house vines at Margate. It was at first treated as 
somewhat of a curiosity, and for many years no steps were taken 
to deal with it seriously. 
On its discovery it was named Oidium Tuckeri, after a Mr. 
Tucker who was the gardener who first noticed it. The next 
year, 1846, it was observed that it had spread considerably in 
the hot-houses in the neighbourhood of Margate. In 1847 it 
was reported from one locality in France. In 1848 it occurred 
_ in several localities in France and also in Belgium. In 1850 the 
vineyards round Paris were seriously affected; the disease was 
also reported from Spain and Italy. In 1851, six years from its 
first recorded appearance in Europe at Margate, the mildew 
was general in all the vineyards in France and in those of the 
Mediterranean basin; it was reported also from Hungary, Greece, 
Switzerland, Syria, Asia Minor, and Algeria. This year it wrought 
wholesale devastation in several districts in France. In 1852, 
1853, and 1854, all the French vineyards without exception 
were invaded to such an extent that their yield of grapes sank 
to a tenth or even a twentieth of the usual crop. The effect of 
this epidemic on the economic conditions of the country was 
such that in certain districts the population had to emigrate. In 
Madeira the industry of vine-growing was blotted out. In all 
the countries affected, Government Commissions were appoint- 
ed to investigate the matter, and voluminous Reports were 
issued, in which is found recorded the consternation which this 
new disease caused among all those connected with grape-grow- 
ing, as well as an account of the enormous loss—amounting to 
many millions of pounds sterling—which this one disease oc- 
casioned to the revenues of the countries concerned. 
The disease by about 1855 had reached its climax as regards 
its epidemic nature, and during the years 1855-60 it was less 
devastating and the harvest of the vineyards was estimated at 
from one-third to one-fourth of the normal yield. It was 
