The Potatoe Plague. 105 
from the same causes in previous years. There is no question 
that the vital energies of a plant, if excited beyond a given 
point, are injured in their organization, and rendered unfit 
for the purposes of reproduction. I speak now of those 
plants which are reproduced by cuttings, layers, and tuberous 
appendages growing from them. Florists who, by the nature 
of their business, are obliged to watch the nature of all plants 
propagated by these means, understand the operation of this 
principle, and the individuals they propagate from are gen- 
erally selected with greatest care. The rules which apply 
to other root crops, will not and cannot apply to potatoes, 
because other root crops are reproduced by seed, and cannot 
be produced by cuttings, sets, or tubers. The potatoe set is 
part of the plant; it is forced from its parent stem to perform 
the unnatural office of perpetuating its kind. Now, this fact 
borne in mind, it will be seen that the causes which I have 
named as producing disease, are the most obvious, as well as 
the most natural ones, and it is the simplicity of the thing 
alone which has prevented the deeply learned and scientific 
from making the discovery before. They have undoubtedly 
made observations on these causes and understand fully the 
operation of them, but as they were simple and evident, have 
passed them by as of no immediate consequence. , 
The same thing may be remarked with regard to progress 
in morals, religion, and any of the sciences. Professors in 
these branches of knowledge, have not distinguished them- 
selves, by any wonderful additions to their subject ; they only 
adopt, apply, and illustrate nown truths. New discoveries 
they make not; they are things unknown; they search for 
them, indeed, but look for profound and mysterious laws, 
forgetting that all the truths in the arcana of nature, are so 
simple that a child can understand them. This rule of 
thought and action has prevented progress from the earliest 
ages to the present time, and a modern professor will be as 
