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Webster 1913 Edition
Protagon
Pro′ta-gon
,Noun.
[
Proto-
+ Gr. ἀγών
a contest. See. Protagonist
. So called because it was the first definitely ascertained principle of the brain.] (Physiol. Chem.)
A nitrogenous phosphorized principle found in brain tissue. By decomposition it yields neurine, fatty acids, and other bodies.