One of the papers chosen by Ray Goldstein in his survey of gems in the old literature (Physics Today, September 2018, page 32) is by Theodor Engelmann, who used oxygen-sensitive putrefying bacteria to determine the wavelength dependence of photosynthesis. Engelmann (1843–1909) made important contributions to physiology, botany, and photosynthesis; less well known is that he was an excellent cellist and a close friend of Johannes Brahms, who dedicated his String Quartet no. 3 to him. Engelmann, in turn, sent Brahms his scientific papers. When in Utrecht, the Netherlands, Brahms often stayed with Engelmann and his wife Emma, herself an eminent pianist, and played chamber music with them.
Known for the brevity and haste of his correspondence, Brahms wrote an unusually long, light-hearted, rambling letter to Emma after he received her husband’s papers. In his letter, Brahms whimsically links the dissolved O (oxygen) that attracts the bacteria (aerotaxis) to the ohs and ahs that art evokes in sensitive persons and he wonders what music would be without these. Styra Avins included and discussed the letter in Johannes Brahms: Life and Letters (1997; letter number 403).
