400 WISCONSIN STATE AGRICULTURAL SOCIETY . 
Dr. Walsh, of Illinois, is said to have thought this disease was 
caused by the puncture of an insect in depositing its eggs, intro¬ 
ducing at the same time some poisonous element, which pervaded 
the branch. But for the memory of that ardent and indefatigable 
entomologist, I trust he was not fully understood in his position; 
as was frequently true of him. 
J. C. Cover, our late and well remembered friend of horticul¬ 
tural progress, advocated the poison sap theory, but as proceeding 
from “ malformed crotches.” 
After an animated discussion of this disease, some twenty as 
observing and practical men as can be found in the west, at a 
meeting of the Illinois State Horticultural Society in 1862, an 
effort was made to convert the society in favor of the insect 
theory, but the society finally confessed its ignorance of the true 
cause, and dropped the matter, only one man hiuting at defective 
circulation as the true cause. 
That veteran, energetic and radical horticultural writer, Thomas 
Meehan, in a paper read at the meeting of the American Pomo- 
logical Society at St. Louis in 1867, presents “ fungus theory ” as 
a foregone conclusion, to which he is committed sure, but finally 
says: “ The fungus which, I think, I may say, causes the fire 
blight , germinates either in or on the bark, pushing its way through, 
the tissue, causing fermentation and death as it goes, and the 
minute fungus plants propagate themselves by small seeds, just 
as larger plants do, and require some time before they perfect 
their reproductive organs.” He therefore recommends cutting 
away and burning the first crop of affected parts, as a prevention 
of its further progress. 
Dr. J. P. Kirkland says, of the various theories of “insect, 
frozen sap, electricity, excessive evaporation and exhaustion of 
the soil, they should all be abandoned, and a cause be sought in 
some other direction,” and gives the following propositions. “ That 
pear tree blight is produced by the poisonous impression of the 
seeds of microscopic fungus.” “That several combinations of 
iron will to some extent counteract that impression.” But Dr. K. 
wishes it to be understood that these propositions are “merely 
hypothetical.” 
Dr. Hull in his report as State Entomologist (Ill. 1869) treats of 
