544 On the Nature and Causes of the Decay in Potatoes. 
Germany. This year potatoes, not stored, contain at least 75 per 
cent, of water, often much more. 
Proportion of Water in Healthy and Diseased Specimens of 
Stored Varieties of Potatoes. 
Healthy. Diseased. 
Keswicks . . . .75-3 80-7 
.... 75-5 81-3 
York Reds .... 72-8 79-0 
.... 67-3 74-7 
Kidneys . . . .71-4 75 '7 
Shaw's . . . .72-1 83-0 
Every well-observed fact may be made to coincide with this 
explanation of the cause. It was a matter of surprise that ill- 
drained lands often had their potatoes less diseased than those 
which were drained, and this arose simply from the same fact 
which rendered the sandy soils on mountainous districts so free 
from it, viz., that the potatoes did not take such a start on these 
in the early sunny months, and that they came to maturity more 
slowly, but more in the order of natural growth. 
Recollect that the potato is not the only plant which has suffered 
from this irregular weather ; turnips also have been partially af- 
fected, and apples refuse to keep as usual. As the disease con- 
sists in a feeble formation of the cellular tissue, the potato was 
perfectly certain to be the plant most likely to suffer, because its 
tuber being a mere enlargement of the cellular tissue, and its sap 
containing a large proportion of soluble albumen, instead of 
insoluble gluten, as in the turnip, was more prone to decom- 
position. 
If I have made myself intelligible, and have carried you along 
with me in conviction, you will understand that I conceive the 
disease to be a chemical decay, passing, if allowed, into putre- 
faction, and that the cause of this decay is an imperfect formation 
of the walls of the cells in the j)otato, produced by the rapid 
growth at first, the imbibition of much water, and the absence of 
sun at the time when the plant most required it. The disease, 
in fact, is a consumption in the potato, just as the same disease 
attacks a youth who has grown too fast and has his organs not 
durably developed. 
This being the case, it is, of course, no new disease — it must 
have existed ever since the potato itself; and M. Boussingault 
informs us that at Bogota, in America, where the plant is indi- 
genous, the disease has been known long — so long that the Indians 
do not know of its having been introduced. 
It has certainly been known in the United States and in Canada 
for several years, and in Ireland isolated instances have been 
