Mid 19th century; earliest use found in Edwin Lankester (1814–1874), public health reformer and natural historian. From prothallus + scientific Latin -ium.
Definition of prothallium in US English:
prothallium
nounprəʊˈθalɪəm
Botany
Prothallus.
Origin
Mid 19th century; earliest use found in Edwin Lankester (1814–1874), public health reformer and natural historian. From prothallus + scientific Latin -ium.