Niels Kaj Jerne, FRS (December 23, 1911 – October 7, 1994) was a Danish immunologist. He shared the Nobel Prize in Physiology or Medicine in 1984 with Georges J. F. Köhler and César Milstein "[f]or theories concerning the specificity in development and control of the immune system and the discovery of the principle for production of monoclonal antibodies".

Jerne is known for three significant ideas. First, instead of the body creating antibodies in response to an antigen, Jerne postulated that the immune system already has the specific antibodies it needs to fight antigens. Second, it was known that the immune system learns to be tolerant to the individual's own self. Jerne postulated that this learning took place in the thymus. Third, it was known that T cells and B cells communicate with each other. Jerne's network theory proposed that the active sites of antibodies were attracted to both specific antigens (idiotypes) and to other antibodies that were bound to the same site. The antibodies were in balance, until an antigen disturbed the balance, creating an immune reaction.

Ludwig Hirschfeld Mack (born Frankfurt-am-Main 11 July 1893, died Allambie Heights, in Sydney 7 January 1965) was a German/Australian artist.

His formative education was 1912-1914 at Debschitz art school in Munich, and 1922 at the Bauhaus-University Weimar where following Kurt Schwerdtfeger he further developed "Farblichtmusiken" ('coloured-light-music'), a light and colour modulator which provided a visual translation of music; in fact an early form of multimedia. Hirschfeld Mack was joint participant, with the former Bauhaus master Gertrud Grunow, in the Second Congress of color-sound research in 1930 in Hamburg. Music and colour theory remained life-long interests, informing his art production in a number of media, and it was the inspiration for his well-respected and influential teaching.

Hirschfeld Mack was born in Frankfurt am Main and attended Arts and Music School in Frankfurt, and later was taught by Hermann Obrist and Wilhelm von Debschitz in Munich, taking art history with Heinrich Woelfflin and Fritz Burger. During the First World War, Ludwig Hirschfeld Mack was an infantry officer.