"Dr Fitzbishop had said, rubbing his hands, that the Luga laboratory said it was the not always lethal 'arethusoides' but it had no practical importance now, because the unfortunate music teacher, and composer, was not expected to spend another night on Demonia, and would be on Terra, ha-ha, in time for evensong. Doc Fitz was what Russians call a poshlyak ('pretentious vulgarian') and in some obscure counter-fashion Van was relieved not to be able to gloat over the wretched Rack's martyrdom." (1.42): A.Sklyarenko informs that "Arethusoides comes from Arethusa, a nymph who fled from her home in Arcadia beneath the sea and came up as a fresh water fountain on the island of Ortygia in Syracuse, Sicily." He adds: "Btw., Arethusa bulbosa is an orchid and Arethusana arethusa is a butterfly from the subfamily Satyrinae."
Jansy Mello: Van's jealous impulse to punish Ada's lovers has a blend of sadism and snobbery (how dare other mortals compete with him for his love?).
An initial reference linked to Rack in the chapter selected by A.Sklyarenko has Van inquire about "dentists":
"Do you know Kalugano? Dentist? Best hotel? Concert hall? My cousin's music teacher?"[ ]She had not been aware that Ada took music lessons. How was Ada?"Lucette," he said, "Lucette takes or took piano lessons. ’
and later, in an imaginary speech, we discover how he tries to multiply Rack's present suffering, including the piano teacher's "web of toothaches":
"We must face therefore the possibility of some prolonged form of disorganized consciousness and this brings me to my main point, Mr Rack. Eternal Rack, infinite "Rackness" may not be much but one thing is certain: the only consciousness that persists in the hereafter is the consciousness of pain. The little Rack of today is the infinite rack of tomorrow — ich bin ein unverbesserlicher Witzbold. We can imagine — I think we should imagine — tiny clusters of particles still retaining Rack’s personality, gathering here and there in the here-and-there-after, clinging to each other, somehow, somewhere, a web of Rack’s toothaches here, a bundle of Rack’s nightmares there ... I submit that the surviving cells of aging Rackness will form such lines of torment, never, never reaching the coveted filth hole in the panic and pain of infinite night. You may answer, of course, if you are versed in contemporary novelistics, and if you fancy the jargon of English writers, that a ‘lower-middle-class’ piano tuner who falls in love with a fast ‘upper-class’ girl, thereby destroying his own family, is not committing a crime deserving the castigation which a chance intruder —’( I,42).
Poor Rack's gums, too, had been a matter of depreciatory comments by Van: " Presently the pianist, floating up and showing his awful gums in a servile grin, tried to draw Ada into the pool from her outstretched position..." (1,32) ...Philip Rack was trudging up, Adam's apple bobbing,ill-shaven, livid, gums exposed, one hand on his chest, the other clutching a roll of pink paper (1,33) ... ‘I think,’ said Van, ‘we’ve got hold of the wrong lover. I was asking about Herr Rack, who has such delectable gums and also adores you to the point of insanity." (1,41). *
When A.S brought up the associations to the word "arethusoides" he mentioned a water nymph named Arethusa and he also added information about butterflies and orchids.
I can now offer another tidbit related to Rack thanks to his initial diligence:
According to a few sources the "Arethusa bulbosa's bruised bulbs (are) useful for the tooth ache, and in cataplasms fur tumors. [ Cf. Schoepf" and Medical Flora, or Manual of the Medical Botany of the United States of North America, Vol. 2, 1830, written by C. S. Rafinesque."
Data on this kind of medical application for the orchid's crushed bulbs could have been part of VN's knowledge about orchids - and he was, most certainly, equally aware of the mythological Arethusa. If these elements inspired him to compound Dr. Fitzbishop's explanation for Philip Rack's afflictions, he must have juggled with their almost hidden associations to dental problems and, therefore, they must carry no further connections to the plot. He'd be playing like Van, perhaps, who saw himself as "ein unverbesserlicher Witzbold."
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*- 207.19: gums exposed: Cf. Rack “showing his awful gums” (200.11); Van contemplating attacking Rack, since he is not born a gentleman and therefore not duellable: “you could make his gums bleed with repeated slaps or, still better, thrash him with a strong cane” (294.28-29); “I was asking about Herr Rack, who has such delectable gums” (296.25-26). Cf. Brian Boyd - Ada Online annotations.