The Potatoe Plague. 51 
neither do I see any reason even to guess such a cause of the 
potatoe plague. . 
A great number of experimentalists contend that the pota- 
toe rot is attributable to the fermentation of animal manure, 
and it strikes me, forcibly, that the rapid, malignant rot of a 
great proportion of the lost crops, may justly be attributed 
to this cause. More instances where the result of this mode 
of treatment has proved fatal to the plant are adduced than 
of any other. I cannot altogether withhold credence from 
such a mass of concurrent testimony. Wherever potatoes 
hare been manured with animal matter, and especially barn- 
yard inanure, in the hill, and when they have been planted 
before such compost has been allowed to disintegrate and as- 
similate with the soil, the rot seems to have been the invaria- 
ble conseqnence. On the other hand, it appears that the 
disease seldom appears on virgin soil, or newly broken sward 
land. JI the more incline to the belief that this theory is more 
extensively corroborated in practice than any of those I have 
thus far noticed, from the fact that, of the potatoes treated 
with animal manure, those which lie nigh the outside of the 
hill are found best and soundest, while those in the centre, 
among the manure, are most specked and rotten. 
It ir not conclusive, however, that the disease can be stop- 
ped by planting on new or sward Jand, inasmuch as potatoes 
dug from such land sound, have often been found to rot after 
storing, so as to have been entirely lost before spring. Neith- 
er does this solution of the mystery suffice, even partially, to 
account for the extent of the injury in other countries; for 
we do not know how potatoes are manured there, or whether 
they are manured at all. All that can be predicated on the 
evidence before us is, that manuring with new animal matter 
is calculated to cause loss and Injury. 
There is yet another theory that I feel bound to notice in 
this connection, inasmuth as it is advanced by a very intelli- 
gent gentleman, (Mr. Teschemacher, of Boston,) as the result 
