Paresis, which is nerve-related weakness or partial paralysis.
From the dates of onset you can see he was suffering from the toxaemia for two months but the paresis only onset in his last week. It would seem logical that the paresis occurred secondary to gangrene although the death certificate does not state where he was experiencing paresis.
Added: Go back to the death certificate on FamilySearch and go back one page. There is a note for death additional information for Ernst that reads:
Kindly have physician state whether this was paresis of the insane or should it be regarded as senile paresis.
Under which is written:
This suggests that this was a central nervous issue, possibly showing signs of dementia as well as weakness/paralysis. Although whether or not it was related to the toxaemia we can never know.