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specifically marked disease, like the potato rot, can be due alone to at¬ 
mospheric influences. 
Neither the insectile theory, nor that of local origin, nor of chemically 
embalmed soils, is, in our judgment, worthy of serious refutation. Al¬ 
though there are certain elements—component parts—of the soil which 
are more or less essential to the existence and growth of the potato, the 
restoration of those elements, of the alkalies, lime, and phosphates which 
enter so largely into their composition, does not necessarily restore the 
equilibrium of the soil so as to prevent a disturbance in the vitality of the 
plant itself. The life of the plant is as perfect in one condition of soil as 
in another ; in fact, it would seem that an enfeebled condition of soil is 
more favorable to the perfect development of the plant as such —to the 
consummation of its life-principle in the production of seed—than even 
a rich or strong condition of soil. Besides, it is wholly improbable, not 
to say impossible, that the soil upon any considerable portion of earth’s 
surface, should have become all at once chemically unbalanced so as to 
occasion a general disturbance as is manifested in the vitality of the 
potato. 
We shall close our observations upon the different theories of disease 
by a reference to a somewhat novel theory which has been suggested by 
a learned and practical horticulturist in the State of New York. It is 
the relation between bearing seed-balls and the health and hardiness of 
varieties. The theory is based upon the supposition that seed-ball bear¬ 
ing is a test of hardiness. The author says, “a variety of potatoes can¬ 
not reasonably be expected to bear a heavy crop of balls and tubers at 
the same time. Both balls and tubers are the result of elaboration in the 
foliage. The material thus elaborated is derived from the air and earth. 
Now, if in a given position one variety bears a heavy crop of sound tu¬ 
bers, it is not to be expected that another variety should do the same, 
and also yield a heavy crop of balls—since, in the last case, the draught 
made upon the elaborating energy of the plant must have been at least 
double that of the other; and as the seeds of all plants always contain 
more mineral ingredients derived from the soil than simple wood, bulbs, 
or tubers, so, in the case of large crops of potato balls, there is propor- 
tionably larger quantities abstracted of important material from the soil 
than in the case of a simple variety of tubers. No one expects that, 
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