Which preposition to use with plutocracy

in Occurrences 1%

A large part of the Italian Press, which repeats at haphazard the commonest themes of the French Press instead of wishing for a more intense revival of commercial relations with Germany, frightens the ignorant public with stories of German penetration; and the very plutocracy in France and Italythough not to the same extent in Italyabandons itself to the identical error.

of Occurrences 1%

The Ivory Tower (called so characteristically after an object whose bearing upon the intrigue is of the slightest) is a study of wealth in its effect upon the mutual relations of a small group of persons belonging to the plutocracy of pre-war America.

Which preposition to use with  plutocracy