Francesco Redi, Florence, 1664 (Google Books)

Redi’s study of vipers was written primarily to understand the physiology of venom.  Redi wrote the work to Lorenzo Magalotti, secretary of the Accademia Cimento.

In a virtuosic display of scientific observation, Redi identified the location of the viper’s poison and explained its toxic effect.  It was thought that vipers were thought to be immune to their own poison, and thus viper fat and flesh were utilized commonly as a therapeutic, composing one of the most famous medications in the ancient world, theriac.

Redi questioned this claim and also discovered that venom was only effective when introduced to the bloodstream via the snake’s bite.  He also was one of the first to realize that a ligature above the wound would allay the ill effects of the venom by preventing it from reaching the heart.  Redi was probably observing the species Vipera aspis hugyi, which occurs only in Italy and which can be seen in a video here.

In his later Sex Exercitationes Medicinales (1694), Lister attempted to explain the spread of disease by insect and snake bites, an interest that may have been generated from his reading of Redi as a student.