408 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1914. 
relatively great increase in activity in this field in the last two decades. 
Activity is the gauge of life, and fullness of life should be the best 
criterion of progress. But we all recognize that whether or not 
activity or life in any scientific field does measure progress depends 
upon whether or not action is directed toward the solution of funda- 
mental problems. 
Let us with this in mind review the progress in phytopathology, 
trying to define and delimit some of the chief problems as they have 
successively arisen and to decide in how far they have been solved. 
IIi.— THE PROBLEM OF PARASITISM. 
Practical-minded men have faced the problems of disease in plants 
since plant culture began and those more scientifically minded have, 
of course, speculated or investigated in the matter. But it will 
profit us little to go back much more than a century for inquiry into 
either their definition of the problems or t heir progress in the solution. 
When Count Re, of Italy (1807),! following the lead of the Tyrolese 
von Zallinger (1773), attempted an account of what was known about 
plant diseases, practical or scientific, the result was largely barren 
because he had no conception of the meaning of parasitism. Little 
was known about the fungi and less about their host relations. 
Schweinitz, Persoon, and Fries soon laid the secure foundations for 
mycological nomenclature and species descriptions, secure because 
based on keen observations and critical comparisons. But they had 
no concern. with plant pathology, aud their contemporaries who had, 
were star-gazing with the nature philosophers. Thus Count Re’s 
work remained nearly half a century after it was published as a stand- 
ard writing in plant pathology.’ 
It required the plague of the potato disease and the example of 
the Irish famine finally to focus attention upon the fundamental 
problem—the relation of the mildew to the sick potato plant, of the 
smut and rust fungi to the infected grain—the problem of parasitism. 
True, they had been phrasing the term parasite much as we do, but so 
long as most held that the so-called parasitic fungus originated through 
the transformation of the sap or the degeneration of the diseased host 
tissues there could be no real progress in plant pathology whether 
scientific or practical. To De Bary’s master mind we owe the clear 
recognition of the parasitic relations of fungus and host plant,? and 
from his demonstration of this we date further progress. 
1 Re, Fillipo. Saggio teorico pratico sulle malattie delle piante. Veneziae, 1807. An English transla- 
tion was published in Gardiner’s Chronicle, 1849, p. 228. 
2 The editor of Gardiner’s Chronicle (1849, p. 211) prefaces the translation of Re’s work withthe statement 
that “it is the best work within our knowledge”’ upon this subject. 
3De Bary, A. Untersuchungen iiber die Brandpilze und die durch sie verursachten Krankheiten der 
Pflanzen mit Riicksicht auf das Getreide und andere Nutzpflanzen, 1853. 
