Wells showed that the coloring matter in the blood was not iron but a complex organic substance subsequently identified as hematin.

David Pitcairn is accredited with the first reference to rheumatism as a cause of cardiac disease, in a lecture given in 1788. Jenner read a paper on the same subject in 1789, but the first clinical report on the subject to be published was that by Wells. Reprinted in Willius & Keys, Cardiac classics, 1941, pp. 294-312.

Wells was the first to notice the presence of blood and albumin in edematous urine. He also established the fact that the edema occurred in the upper parts of the body, and he described the uremic seizures to which such cases are liable.

For this work Wells was awarded the Rumford Medal of the Royal Society. His researches on the subject were of major importance in the development of the science of ventilation, particularly in its relation to relative humidity and the influence of the latter on the comfort of the occupants of factories, ships, theatres, etc. Wells was physician to St. Thomas’s Hospital, London, from 1800 until his death.

First statement of the theory of natural selection. Wells’s paper on a white woman with patchy brown discoloration of the skin contains an almost complete anticipation of Darwin’s theory of natural selection, although it was completely ignored until it was resurrected by a correspondent of Darwin in the 1860s. The volume also contains Wells’s autobiography. See no. 1604.