Willis’s last work deals with the anatomy and physiology of the thoracic and abdominal organs, and contains the first description of the superficial lymphatics of the lungs, the first clinical and pathological account of emphysema, and a clear and accurate description of pertussis (whooping-cough). The book also contains the first distinction between diabetes mellitus, characterized by glycosuria, from diabetes insipidus, in which sugar is not present in the urine. Willis noted that psychogenic factors, such as grief or sadness, could bring on diabetes. The second volume, published posthumously, includes a life of the author.

Three versions of Willis’s book were published simultaneously: A quarto version with the imprint of the Sheldonian Theatre in Oxford, another quarto version with the London imprint of Robert Scott added, and a duodecimo edition

"Epidemiorum et ephemeridum libri duo, pars secunda" in vol. 2 contains (p. 99) a description of “puerorum tussis convulsiva, chincough dicta” – a clear account of whooping cough (Treatise IX, pt. 2, p. 38 of his Practice of physick, 1684).