GLOSSARY* 
Agent of inoculation.—The thing which acts as the carrier in the transfer 
of the inoculum from its source to the infection-court, as for example :— 
wind, insects or running water. 
Control.—The prevention of losses from a disease. Every control measure 
is based on one of four fundamental principles; exclusion, eradication, 
protection or immunization. 
Dissemination.—The act or manner of scattering or spreading the inocu- 
lum of the pathogene within an immediate and more or less limited 
area about the source of inoculum. 
Distribution.—(a) The act of transporting and establishing a pathogene 
beyond barriers in other regions. (b) The geographical occurrence 
of the disease; synonymous with range. 
Ecology.—That phase in the study or discussion of a disease which deals 
with the relation of environmental factors to its occurrence, severity 
and character. The ecologic factors are chiefly, climatic, soil and 
cultural. They influence the disease indirectly through their in- 
fluence on the pathogene or the host or on both. 
Enphytotic.—The opposite of epiphytotic. An enphytotic disease is one 
regularly occurring in a locality or region and not liable to marked 
variations in: destructiveness. Re 
Epiphytotic—The sudden and destructive appearance of a plant disease 
in a locality or region. An epiphytotic disease is one the past history 
of which shows it to have a tendency to appear suddenly and destruc- 
tively, usually over large areas at rather long intervals. The term 
is analogous in meaning to epidemic but not synonymous with it. 
Eradication.—The principle of controlling a plant disease by removing 
or destroying the pathogene already established within a given area 
or region. Disinfection, seed-selection, crop-rotation and: the like 
are eradicatory measures. 
Etiology.—That phase in the study or discussion of a disease, which deals 
with the chief causal factor, the pathogene, its nature, character and 
relations with the host. : 
Exclusion.—The principle of controlling a disease in plants by excluding 
the pathogene from a given area or region. Inspection and quaran- 
tine are the exclusionary measures usually employed. ; 
History of a disease.—The logically arranged historical facts, relating to 
the disease itself, as distinguished from those relating more es- 
pecially to the pathogene. ; : 
‘Host.—The plant affected with, or subject to a given disease. 
Hyperplasia.—That type of pathological condition expressed by abnormal 
increase in the number of cells, that is, excessive cell-division. 
Hypertrophy.—That type of pathological condition expressed by abnormal 
increase in size of cells (dimensions or volume). The term is also 
commonly used. in a less restricted sense to designate swellings or 
overgrowths of various kinds, due either to abnormal increase in 
the size of the cells or abnormal cell-division or both. (See p. 8.) 
*The definitions apply to the respective terms only as these terms are used in 
a phytopathological sense, and particularly as used in these outlines. The definitions 
do not always agree with those to be found in dictionaries, nor always with the variety 
of senses in which the terms are used even in phytopathological literature. 
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