Traces of Modern Vascular Ultrasound in Historical Research Works of Lazzaro Spallanzani and his Disciple Giovanni Battista Venturi

The first surprising notes concerning bats in Spallanzani’s notebook date back to the summer of 1793. In his father’s house in Scandiano, where he passed his summer holidays free from all duties of natural history teaching at Pavia University, he was drawn to the phenomenon of night flight of birds of prey. Over the following two years , the experience built up at Scandiano fort and later at Pavia University allowed Spallanzani to describe these creatures ability to sustain night flight through the hearing mechanism. In this way, for the first time in the history of science the intuition of sound signals outside of man’s experience was noted down. Furthermore, in bats observed by the naturalist  in the eighteenth  century, these signals emerge as ultrasound and appear in such a way that evoke modern echography. A few years later (1797), his disciple Giovanni Battista Venturi  occasion of a diplomatic
mission in Paris announced  the results of his experimental enquiries concerning the principle of lateral communication of motion in fluids. This work highlights the phenomenon of acceleration of the fluid due to the decrease of the calibre of the conduct which is the basis of modern algorithms implemented in the tools of vascular diagnosis by echo-doppler. The application of ultrasound in medical imaging had to wait for the discovery of piezoelectric phenomenon by the Curies in 1880 and subsequent undersea exploration with sonar during the First and Second World War.  However the primordial intuition of transmitting ultrasonic energy found in the auditory system of bats and the description of the movement of fluids within the stenotic vessels are due to the tough discipline and rigorous experimental method adopted by the abbots Lazzaro Spallanzani and Giovanni Battista Venturi.