Drawing of the 1918 Influenza: Lymph sinus, some of the cells shown in their protoplasm - small clean spaces containing two, three or four fine deep brown spherules - shadows of colon bacilli

Licence: Attribution 4.0 International (CC BY 4.0)

Credit: Drawing of the 1918 Influenza: Lymph sinus, some of the cells shown in their protoplasm - small clean spaces containing two, three or four fine deep brown spherules - shadows of colon bacilli. Wellcome Collection. Source: Wellcome Collection.