The conducting nerves between the brain and the spinal marrow have been overworked: too much activity, too constant a strain.

Even the rails and sleepers on the railroad wear out, don't you know, if there's excessive traffic.' Mr.Horton had known Mary from her childhood, had given her Gregory's powder, and seen her safely through measles and other infantine ailments, so he was quite at home with her, and at Fellside generally.
Lady Maulevrier had given him a good deal of her confidence during those thirty years in which he had practised as his father's partner and successor at Grasmere.

He used to tell people that he owed the best part of his education to her ladyship, who condescended to talk to him of the new books she read, and generally gave him a volume to put in his pocket when he was leaving her.
'Don't be downhearted, Lady Mary,' he said; 'I shall come in two or three times a day and see how things are going on, and if I see the slightest difficulty in the case I'll telegraph for Jenner.' Mary and the Fraeulein sat up with the invalid all that night.

Lady Maulevrier's maid was also in attendance, and one of the menservants slept in his clothes on a couch in the corridor, ready for any emergency.

But the night passed peacefully, the patient slept a good deal, and next day there was evident improvement.