In this response to Haller's Deux mémoires sur le mouvement du sang (1756) (No. 11607) Spallanzani outlined his own findings on the action of the heart upon the blood vessels. "Haller's microscopic observations of blood movements had been made by refracted light on midium-sized vessels in the isolated mesontery of the frog. Splallanzani, using P. Lyonet's novel dissecting apparatus, conducted his observations mostly in a darkened room with reflected light from sunbeams impinging upon exposed parts of the aquatic salamander. He systematically noted now the cardiac systolic force motivated the blood circulation. The rhythmic inequality of blood flow in the aorta and large vessels disappeared in medium and small arteries, becoming regular and uniform. The velocity diminished in the smaller vessels, but sinuosities did not retard the flow. In the smallest vessels, individual red corpuscles negoiated acute angles and folds by elastically changing shape. The blood velocity in the venous sytem increased as the caliber of the vessels enlarged. Haller responed to the many amplifications and corrections of his work by securing Spallanzati's election to the Royal Society of Sciences of Gottingen" (Dolman, DSB 12, 553).

 Digital facsimile from Google Books at this link.