Note 13 — Chapter I · On the Intimate Relation existing between the Deterioration of Beer, or the Wort from which it is Made, and the Process of Brewing.
Frank Faulkner translation
A convincing proof of the influence of hops on the ferment organisms is contained in the fact that beer, even after being raised to 60° C. or 70° C. (140° or 160° F.), will, if unhopped, readily take on the butyric fermentation, from which, if hopped, it would remain perfectly free.