One labour carries the whole address. The hydra had “a huge body, with nine heads, eight mortal, but the middle one immortal” [The Library (Bibliotheca), BOOK II, ch. V]. The arithmetic of the fight is the motif’s logic: “as fast as one head was smashed there grew up two”, until Iolaus, “burning the roots of the heads with the brands, prevented them from sprouting” [ibid.]. The immortal ninth cannot be killed, only administered: Hercules “chopped off the immortal head, and buried it, and put a heavy rock on it” beside the road through Lerna — the undying thing is still there, under a landmark [ibid.]. Two codas: he slit the body and “dipped his arrows in the gall”, arming the rest of his career with this one monster; and Eurystheus refused to count the labour because “he had not got the better of the hydra by himself” [ibid.]. Frazer’s note tracks the head-count inflation — “Diodorus and Ovid multiply the hydra’s heads to a hundred” [ibid., editor’s note] — which makes Thompson’s precise nine-head address an edition-specific fact, true of the text we serve. His single apparatus row is that note, resolved.