Thomas Beddoes to Erasmus Darwin, [1794–1802] [fragment]
I have at present a patient who miscarried near the end of her fourth month and had much haemorrhage. Whenever she goes to sleep she has convulsive twitchings of many of her muscles, but not at other times. There appear to be two distinct causes for the convulsive motions that happen in sleep, or in going to sleep. – 1. The accumulation of sensorial power so well explained by you. 2. The other is the want of control of the voluntary power: occurring under circumstances where you cannot well suppose the excitability to be accumulated. This is well illustrated in some of Fowler’s experiments, (On animal electricity) where, upon applying the two metals to an entire frog, he produces convulsions or not, according as the animal is or is not aware of the application: so that his exertion will, in the former case, stop those movements which the irritation would otherwise occasion.
Published: Stock, p. 249