Proceedings 23 
like cells, which being very light and small, are blown by 
the wind to the host-plant. 
The view has also been advanced that fresh infection in 
the Spring may be caused, not by ascospores, but by hiber- 
nating conidia, or by hibernating mycelium. This view 
has one very strong fact to support it, for it certainly does 
seem as if occasionally a mildew is able to appear year 
after year and yet never produce ascospores. 
There is this well-known, historic example :— 
In 1847, the British mycologist, Berkeley, described 
under the name Ozdium Tucker, in the “Gardeners’ Chron- 
icle,” a fungus which was attacking grapes at Margate. 
This O:dium Tuckeri appeared almost immediately in all 
the vineyards of the Mediterranean, and by 1851 it caused 
wholesale destruction throughout vast grape-growing dis- 
tricts in France, Switzerland, Germany, Italy, Spain, Algeria, 
and Asia Minor So complete was the devastation caused 
by this mildew that, in consequence, in many districts the 
vineyards were destroyed. For several years hundreds of 
thousands of pounds were lost to the vineyard owners. 
Now, although the fungus was so terribly prevalent, no 
perithecia were found in connection with it for the first 
forty-seven years of its occurrence, the conidial form of the 
fungus alone being observed year after year. We may feel 
pretty sure that really no perithecia were produced, at any 
rate for the first ten years or so of its occurrence, because, 
so to speak, a price was set upon the head of the fungus, 
The governments of the countries affected (at least those 
governments which patronize Science—the English govern- 
ment was not among the number) offered large sums of 
‘money to induce botanists to investigate fully the life- 
history of the fungus. Notwithstanding this, no perithecia 
could be found by investigators. 
Not until 1892 was this form of fruit discovered in France, 
when a few perithecia were found in one vineyard. Last 
-year I received from Germany a few perithecia which had 
_ been produced on the stalk of a bunch of grapes. 
It seems impossible even now, when perithecia are appar- 
ently beginning to be formed by the fungus, that the 
