1 72 On the Prevention of Curl and Dry-Rot in Potatoes. 
siderable effect, and concur with the under-ripening of the seed 
in producing: ^ healthv and vigorous plant. 
The last objection is one which has already proved fatal to 
several theories that have been brought forward to account for 
the potato failure, and may be briefly stated as follows : — " We 
planted, we manured, we harvested our potatoes fifty years ago 
much as we do now, except that the whole was then done in a 
more careless, haphazard way ; yet we were then never troubled 
with the complaint which is now our bane. How can this be 
accounted for except by the deterioration of the plant itself?" 
The causes which produce failure now, and which did not exist 
formerly, may, I think, be referred — 1st, to change of climate ; 
2nd, change of soil; 3rd, change of practice. — 1st. Change of 
climate. The great increase of draining, enclosing, and planting 
for shelter, has produced a very sensible change of climate in ex- 
posed situations, which are the places most in vogue for the 
supply of seed potatoes. In the case of Sawdon, mentioned 
above, enclosure, &c. was at any rate contemporaneous with the 
deterioration of their seed potatoes, and the marshland districts, 
which were formerly supplied from Sawdon, now get their seed 
from Scotland. It is indisputable that both cold and wet retard 
the maturity of all plants : the improved practice of the present 
day has removed the one and very much reduced the other, and 
accordingly our potatoes become more thoroughly ripened and 
make worse sets. To those who are inclined to attach little 
importance to this reasoning, I would put the question — where 
would you go for seed potatoes if you should be troubled with 
curl ? I answer without fear of contradiction, that if you are 
at all conversant with the subject, and have no fresh land that 
you can conveniently break up, you will either send to an ex- 
posed hilly district, or to a peaty moorish soil. Here, then, 
we see that experience guides us to the cold, wet soils, to those 
places, in short, which are highly unfavourable to early maturity, 
and from which we have a good chance of obtainmg unripe seed. 
— 2nd. Change of soil. In spite of the numerous valuable sug- 
gestions which the farmer has already received from the man 
of science, agricultural chemistry is still too much in its infancy 
to be able to specify the exact proportions and combinations 
of the various elements of vegetable life which should exist 
in a soil to enable it to bring to the greatest perfection the crop 
with which it is to be sown ; and accordingly we find that no 
chemical combination of manures that has yet been tried has 
produced a compound in which plants grow with so much health 
and vigour as they do in fresh {i. e. uncropped) soil of good . 
quality. This fact is admitted on all hands ; but let us examine 
it a little more in detail. To say that uncropped soil will grow 
