Paper, 'On the rhythm of the mammalian heart' by J A [John Alexander] MacWilliam MacWilliam writes: 'The following are some of the general conclusions arrived at from a prolonged investigation of the rhythm of the mammalian heart. The experiments were conducted on the cat, dog, rabbit, rat, hedgehog, and guinea-pig, the cat being the animal most commonly used.' Annotations in pencil and ink. Subject: Physiology Received 26 April 1888. Read 17 May 1888. Communicated by Michael Foster. A version of this paper was published in volume 44 of the Proceedings of the Royal Society as 'On the rhythm of the mammalian heart'. 1888