293 
through the decorticated space, and acts powerfully in accelerating the 
growth of fruit. The increased production of fruit is obtained, how¬ 
ever, at the expense of the roots, or of the tree below the decorticated 
space. 
From some experiments and observations made in the summer of 
1851, we were led to adopt a theory of disease upon the hypothesis of a 
too vigorous growth of the 'plant , causing its sap or juices to be too rapidly 
diffused, and uninterruptedly expended, in the formation of the leaf- 
buds, to the exclusion of the fruit-buds, as in the case of young fruit 
trees pressed into excessive growth by artificial cultivation. There 
appeared to be too little compression—too little accumulation of the 
elaborated juices, to effect a perfect development of the fruit-buds, or 
seed-blossoms of the plant, and hence the tendency to blight. We were of 
the opinion, somewhat hastily formed, that the disease was the result 
of repletion, or a too excessive elaboration on the part of the plant; that 
instead of there being superannuation and want of energy, there was 
really superabundance and over exertion. That in pursuing the process 
of amelioration from the original and almost worthless condition of the 
plant in its native state, it had become, through successive generations 
of growth, not exhausted by age, but urged into prematurity and unna¬ 
tural advancement, and beyond its real powers of endurance. There 
seemed to be not only a ratio of perfection between the tubers and seed- 
balls, but a point in their mutual progress of development at which the 
one was forced to yield up its vitality to the other , under circumstances and 
conditions, as to accumulation, maturity, <fcc., which seriously affected, 
if not fatally compromised, the life of the plant itself. We had noticed, 
and were strongly impressed with the belief, that although the potato 
had perfected a less number of seed-balls since the commencement of 
the rot than formerly, there was yet an equal, if not a greater, effort 
on the part of the plant to perfect them, as exhibited in its excessive and 
long-continued enflorescence, or unfolding of blossoms. 
The facts upon which we labored to erect a theory of disease, although 
few, were yet more numerous than harmonizing. In 1850 and '51, our 
potatoes were seriously affected by the rot. No tubers, however, could 
have been more perfect than those raised by us a week before they were 
thus affected. The disease seized upon them at the very moment when 
