332 BULLETIN OF THE BUSSEY INSTITUTION. 
1. What is the nature of the soil on which you have planted potatoes 
this year ? 
2. What crop has preceded the potatoes ? 
3. What was the ‘preparation of the land for potatoes? What 
manures have. been used ? 
4, What varieties of potato have you planted, noting whether the 
varieties were early or late? 
5. What was the date of planting ? 
6. What was the exact date of the appearance of the rot? 
7. What varieties seemed to suffer least from the disease ? 
8. What proportion of the crop was destroyed ? 
9. On first noticing the rot what was done to save the tubers, and 
with what result ? ; 
10. Following a clover crop, how are potatoes affected by the rot, par- 
ticularly badly or not? After potatoes, does clover do well? Have you 
observed any fungus upon clover ? 
11. Following a wheat, oat, or rye crop, how are potatoes affected by 
the rot? When wheat, oats, or rye follow potatoes, what is the re- 
sult ? 
Before proceeding to a consideration of the best means of diminish- 
ing the rot, let us examine some of the supposed objections to the 
fungus theory of the disease. It may be premised that such objections 
are not urged by men of science, and that entomologists as well as 
botanists acknowledge the fungus origin. We must at the outset dis- 
tinguish between potatoes affected by the rot, and rotten potatoes. If 
we take any healthy potato and keep it in a sufficiently wet place, it 
will become mouldy and, finally, rotten. We shall not find any of the 
Peronospora infestans on it, however, but ordinary moulds which live 
upon decaying substances, as Mucor, Penicillium, &c..— moulds which 
can grow on almost any dead matter, but which do not attack living veg- 
etable tissues. In other words, we have put a healthy potato under 
such circumstances that it has begun to decay, and then some of the 
spores of those fungi which live on decaying matter settle upon it, — 
the air is always full of such spores,—and grow. ‘These moulds do 
not attack living potato plants, and are not to be dreaded, because we 
have only to keep the potatoes when harvested in a dry place to avoid 
all trouble. 
In Figs. 6 and 7 are roughly represented two of the common moulds 
