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species, many of which were native economic plants. Seeds of 
about 200 species of herbs, trees, and shrubs, were collected. 
The Curatorship of Plant Pathology was established on January 
1, 1921, with the appointment of Dr. George M. Reed, by means 
of funds provided by Mr. Alfred T. White and two friends. The 
members of the Department have devoted their time almost ex- 
clusively to research. Specific problems have been investigated 
by assistants and graduate students, the results being embodied 
in theses for which they received advanced degrees at Columbia 
University or New York University. 
A definite program for the investigation of disease resistance 
in plants was developed, including such topics as: the determin- 
ation of the susceptibility of resistance of particular hosts, or va- 
rieties, to pathogens; the influence of environal factors upon the 
resistance and susceptibility of hosts; the existence of physiologic 
specialization of pathogens; and the inheritance of the disease- 
resistant quality. 
For the study of disease resistance along the proposed lines, 
diseases of cereals have proved to be especially adapted, and most 
investigations have been made with the cereal smuts, since they 
were particularly interesting for these studies. The smut  path- 
ogen usually invades the host in the seedling stage, but shows no 
evidence of its presence until the heading, or flowering, time of 
the grain, weeks or even months later. 
Physiologic specialization of plant pathogens has been known 
for a long time, but it was not until 1921 that this phenomenon 
was observed in the smuts. The first evidence of physiologic 
specialization in cereal smuts was obtained in studies made at the 
Botanic Garden, and five specialized races of covered smut of 
barley, two of the loose smut of oats and two of the covered smut, 
and ten races of the two species of covered smut of wheat were 
demonstrated in 1924-1927. Most attention has been paid to the 
oat smuts, and at the present time more than thirty races of loose 
smut and fourteen of covered smut are known to occur. 
The characteristics of certain races of oat smuts were compared 
in their growth on artificial media in the laboratory, and new 
races have been originated by combining pure line cultures de- 

rived from two distinct races. 
