How fortunate we didn't have these animal tests in the 1940s, for penicillin would probably not have been granted a licence, and possibly the whole field of antibiotics might never have been realised.

The context is: "the present approach to drug safety evaluation, based on experimental animal studies, is known to be of questionable scientific veracity and has never been satisfactorily validated as an appropriate surrogate system for man. My former teacher, Sir Alexander Fleming, in his late years, chided me, saying …"