The rest of the examination proceeded without a hitch.  For a minute or two, it is true, I fancied that Sebastian betrayed a certain suppressed agitation—­a trifling lack of his accustomed perspicuity and his luminous exposition.  But, after meandering for a while through a few vague sentences, he soon recovered his wonted calm; and as he went on with his demonstration, throwing himself eagerly into the case, his usual scientific enthusiasm came back to him undiminished.  He waxed eloquent (after his fashion) over the “beautiful” contrast between Callaghan’s wholesome blood, “rich in the vivifying architectonic grey corpuscles which rebuild worn tissues,” and the effete, impoverished, unvitalised fluid which stagnated in the sluggish veins of the dead patient.  The carriers of oxygen had neglected their proper task; the granules whose duty it was to bring elaborated food-stuffs to supply the waste of brain and nerve and muscle had forgotten their cunning.  The bricklayers of the bodily fabric had gone out on strike; the weary scavengers had declined to remove the useless by-products.  His vivid tongue, his picturesque fancy, ran away with him.  I had never heard him talk better or more incisively before; one could feel sure, as he spoke, that the arteries of his own acute and teeming brain at that moment of exaltation were by no means deficient in those energetic and highly vital globules on whose reparative worth he so eloquently descanted.  “Sure, the Professor makes annywan see right inside wan’s own vascular system,” Callaghan whispered aside to me, in unfeigned admiration.

The demonstration ended in impressive silence.  As we streamed out of the laboratory, aglow with his electric fire, Sebastian held me back with a bent motion of his shrivelled forefinger.  I stayed behind unwillingly.  “Yes, sir?” I said, in an interrogative voice.

The Professor’s eyes were fixed intently on the ceiling.  His look was one of rapt inspiration.  I stood and waited.  “Cumberledge,” he said at last, coming back to earth with a start, “I see it more plainly each day that goes.  We must get rid of that woman.”

“Of Nurse Wade?” I asked, catching my breath.

He roped the grizzled moustache, and blinked the sunken eyes.  “She has lost nerve,” he went on, “lost nerve entirely.  I shall suggest that she be dismissed.  Her sudden failures of stamina are most embarrassing at critical junctures.”

“Very well, sir,” I answered, swallowing a lump in my throat.  To say the truth, I was beginning to be afraid on Hilda’s account.  That morning’s events had thoroughly disquieted me.

He seemed relieved at my unquestioning acquiescence.  “She is a dangerous edged-tool; that’s the truth of it,” he went on, still twirling his moustache with a preoccupied air, and turning over his stock of needles.  “When she’s clothed and in her right mind, she is a valuable accessory—­sharp and trenchant like a clean, bright lancet; but when she allows one of these causeless hysterical fits to override her tone, she plays one false at once—­like a lancet that slips, or grows dull and rusty.”  He polished one of the needles on a soft square of new chamois-leather while he spoke, as if to give point and illustration to his simile.