24 
THE POTATO FUNGUS. 
spores from which they were discharged. With this exception 
there has not been the slightest approach in any of my material to 
organisms which might be referred to Pythium. Mr. Plowright 
writes : “None of my oospores ever burst and produced Pythium 
or Pythium-like spores.” 
My material has contained a large number of dead mites and 
aphides and a few nematoid worms ; the oogonia and threads 
were to be seen in all parts of the dead insects, but not in the 
w^orms. 
De Bary, in reviewing my observation, says : — “ Even if the 
often mentioned warty bodies w^ere hibernating oospores of 
Phytophthora (Peronospora), like the similar oospores of P. 
Arenaria? which resemble them, we should not gain much informa- 
tion bearing upon these questions, since their occurrence is, at 
the best, extraordinarily rare.” This sentence is very erroneous, 
for although the bodies were apparently rare when I first recorded 
their discovery, they were not necessarily so in a state* of nature, 
for on continuing the experiments after my first essay was written, 
the resting-spores were produced in myriads, and that, too, within 
the tissues of a comparatively few leaves. During the present 
spring I have sent mounted preparations of the mature (or almost 
mature) resting spores to many of the foremost cryptogamic 
botanists of Europe, but not one has denied their possible identity 
with Peronospora infestans. 
For more than thirty years our potato crops have been systemati- 
cally destroyed by two virulent fungi, viz., Peronospora infestans 
and Fusisporium Solani ; these two parasites almost invariably 
work in company with each other, they suddenly appear for a few 
weeks, destroy our crops, and vanish for ten or twelve months, 
then reappear and repeat the work of destruction. I claim for my 
work that it is new, and that it has proved how both these fungi 
hide and sleep through eleven months of the year. As I have 
kept the resting-spores of both parasites alive artificially in 
decayed potato leaves in water, in moist air, and in expressed 
diluted juice of horse-dung, it conclusively proves to me that the 
resting-spores hibernate naturally in the same manner. The seat 
of danger from both parasites is clearly in dung heaps, ditch sides, 
and decaying potato plants. 
Any method of destroying the resting-spores of these pests, or 
of warding off or mitigating their attacks, obviously depends in a 
great measure upon a full knowledge of their life- history. That 
life-histoiy I have endeavoured to the best of my ability to watch 
and describe for the Gardeners' Chronicle^ nwd 1 am content to 
let the observations stand on their own merits. Sensibly conducted 
and extensive field experiments might probably teach some valu- 
able lessons, but it is difficult, if not impossible, for any single 
individual, whether farmer or botanist, to institute and carry out 
such experiments. — Gardeners' Chronicle, pp. 39-42, 1676. 
