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PREFACE 
HESE outlines are designed solely for the purpose of most effectively 
acquainting the student with the laboratory materials presented 
in this course. They are the result of several vears of experience 
and test in actual practice work. They have been frequently revised. 
It is expected that they will now be revised and reprinted at least every 
two years. 
Although the acquisition of a body of facts is an important and neces- 
sary part of the work in such a course a more vital feature is the training 
in logical methods of acquirmg them. The student is urged to follow 
his outline carefully, making sure at each step, that the outline and the 
materials before him agree. The same sequence of treatment is followed 
throughout all the outlines. This sequence in procedure should be mast- 
ered promptly. The term papers will afford opportunities for determining 
how well the student has grasped the logic of this procedure. _ 
The grouping of diseases here presented is, we believe, an important 
step in diverting attention from the domination of systematic mycology 
in phytopathological teaching and writing, and of directing it toward 
the more logical classification and study of diseases on the basis of the 
pathological phenomena exhibited. At the same time the subgrouping 
of the diseases, according io the chief etiologic factor involved, provides 
for a point of view still generally presented in the teaching of plant path- 
ology. 
t is not expected that all the diseases herein outlined will be covered 
in a three hours’ course. The instructor will make such selections from 
the different groups as will best serve his purpose in illustrating the funda- 
mentals of the subject in the case of the students in his classes. No 
laboratory practice in the methods of control of the diseases studied is 
provided. That phase of the subject is fully treated in the course based 
upon and following this, namely, The Principles of Plant Disease Control. 
These outlines are designed specifically for the work as given at Cornell 
University and without any attempt to adapt them for use in other institu- 
tions. It is hoped, however, that teachers elsewhere may at least find 
them helpful and possibly usable in their classes. 
Acknowledgments are due Mr. Chas. Chupp, instructor in the depart- 
ment of Plant Pathology for the preparation of a number of the outlines. 
We also gratefully acknowledge the friendly advice and assistance of the 
Comstock Publishing Company in our effort to make the cost of these 
-outlines to the student as reasonable as possible. 
THE AUTHORS. 
