288 
On the Cultivated Potato. 
practical considerations ; cultivation means this, — that man, for 
his own purpose, steps in to bar the all-sufficient action of natural 
eelection. 
North American experiences are not very dissimilar to our 
own ; I have consulted various Publications in the Librarv of 
the Royal Agricultural Society. The House of Commons Com- 
mittee sought for American information, which for the most 
part the evidence failed to supply. In reports from the United 
States of America you may find the potato-bug (Don/phoi-a) 
figured in all the " seven ages " of his life, with an account of his 
triumphal march from the Rocky Mountains northwards, " over 
hill, dale, and river : " having fed on the wild potato, he ad- 
vanced to devour the cultivated crops. We read of the culti- 
vated potato-plant as run out, and we are told potato-disease is 
as old as the potato : the writer holds the Peronoxpora infestavs 
theory. Now an all-devouring louse, or aphis, appears on the 
scene to complete devastation. Next we are told that continued 
iiigh cultivation has caused gangrene of the tuber, followed by 
a red-rust fungus, with an insect which lives only in the cor- 
rupted tuber. A writer in the Massachusetts Report of 1854 
marvels at the universality of the disease, which is not occa- 
sioned by blight, insects, fungi, climate, or soils ; the cause, 
over-cultivation, has always been the same, the effects varied. 
The cultivated potato has been subjected to a discipline more 
severe than that which any other plant has ever experienced : 
with abnormal culture the balance is lost, the leaves are 
diminished to encourage the tuber, the energies of the plant 
being withdrawn from its own nutrition ; thus over-stimu- 
lation subjects to decay and climatic influences. We are 
ignorant of necessary conditions. I leave with regret a very 
thoughtful paper to take up another which introduces us to a 
little hard-shell worm, a wireworm, which in low lands effectually 
does its wicked will : next we find a potato-worm, which on the 
whole prefers tomatoes, but it is not very particular, and greedily 
falls-to on the potato — this is the tobacco-worm, when mature, 
the sphinx-moth. There is also another of the legion enemies 
■of the solanum, the three-lined beetle, the Lema trilineata. Well 
might the American writer cry out for a theory that can account 
for all the phenomena, for a remedy to apply generally ! 
I have, in the Spanish language, publications from both sides 
of the South American continent, ably translated for me by my 
friend Major Stuart, late H.M. Minister at Hayti : I have had 
also an obliging communication in regard to the Peruvian au- 
thority from Colonel Jara Almonte, of the Peruvian Legatiorv. 
jMonsieur M. G. Merino, writing at Lima in 1878, treats of the 
epidemics of plants on the coasts of Peru ; he says of the potato 
