On the Nature and Causes of the Decay in Potatoes. 513 
I'lie evidence is also completely satisfactory, that the early planted 
potatoes and those which come to an early maturity have suffered 
least from the disease. All these circumstances point out clearly 
that the disease is connected with the state of season. Recollect 
what has been the kind of weather not only in this country, but all 
over Europe. 
In the early part of the year, when the plants were starting into 
existence, we had a fev/ days of unusually warm weather, which 
gave a great impulse to vegetation. You need not be reminded 
that the products formed in plants are suited to the gradual pro- 
gress of the seasons, and that, as they advance towards maturity, 
they require much warmer weather and more direct solar action 
than in the early stages of their growth. But our last summer 
has been the reverse of this. Its earlier part was characterized by 
an unusually forward season, which gave a rapid impulse to vege- 
tation ; and when this forward vegetation ought to have been sup- 
ported by an increasing action of the sun, we had cold, cloudy, 
and ungenial weather, and few there can be who did not remark 
our sunless season. The herb of the potato in most cases became 
strong and luxuriant bv the warm weather of the latter end of 
June and beginning of July, which, finding the soil moist, gave a 
sharp spur to vegetation. Towards the end of July and begin- 
ning of August a comjilete change came over the weather, which 
now became cold, cloudy, and although sometimes we had a 
sudden outburst of the sun, the season altogether was pre-emi- 
nently sunless — and recollect that this was just the time when 
not only the herb but the tuber required the greatest amount of 
warmth and direct solar action. This was exactly the same kind 
of weather which produced the disease in America in 18-13 ; and 
it is precisely similar to that which has been experienced all over 
Europe in the present year. 
Now in the too rapid growth of the tuber in the alternate 
sunny and rainy days which we had during the early and middle 
growth, an abundance of water entered the plants, and the evapo- 
ration from the leaves being retarded, it was quite impossible for 
the cellular tissue to become firm and durable. In proof of this 
I refer to the various analyses which I have made of the healihy 
and diseased specimens of the same variety of potato — in which it 
will be seen that the diseased potato uniformly contains more 
water, must therefore have its cellular tissue less imperfectly 
formed, and hence is more subject to the disease. These analyses 
have been made upon stored potatoes, and yet the proportion of 
water is generally greater than in former years. I have fre- 
quently had occasion to examine potatoes in other seasons, and I 
found them on the average to contain 72 per cent, of water — a 
result confirmed by Boussingault in France and Bocckman in 
