Group photograph: (l. to r.) Sir W. Simpson, Sir R. Ross, Sir Aldo Castellani, and Sir Malcolm Watson,

Licence: Attribution 4.0 International (CC BY 4.0)

Credit: Group photograph: (l. to r.) Sir W. Simpson, Sir R. Ross, Sir Aldo Castellani, and Sir Malcolm Watson,. Wellcome Collection. Source: Wellcome Collection.