Unlike other forms of investigation, such as microscopy, vivisection was not new in the seventeenth century. Nonetheless, it was developed in new ways and led to a number of strikingly original results. This project examined eight especially prominent cases ranging from William Harvey and Gasparo Aselli to Anton Nuck and Johann Jakob Wepfer. A special focus was placed on the relation to practices of scientific observation. These two forms of investigation may seem antithetic, since vivisection is the archetypal example of an interventionist technique, whereas observation is considered to be passive and non-interventionist; in many cases, however, the analysis has shown that vivisection co-existed with observation and with techniques drawn from natural history.