Which preposition to use with euthanasias

of Occurrences 2%

The time would have come when religion would have carried out her object and completed her course: the race she had brought to years of discretion she could dismiss, and herself depart in peace: that would be the euthanasia of religion.

to Occurrences 1%

" "Does your law," I asked, "confine the principle of euthanasia to infants, or do you put out of the world adults whose life is supposed, for one reason or another, to be useless and joyless?"

Which preposition to use with  euthanasias