Aselli, Or Asellio, Gasparo, an Italian anatomist, born in Cremona about 1580, died in Milan in 1626. He was professor of anatomy in the university of Pavia. In 1622, while demonstrating the recurrent laryngeal nerves by the dissection of a dog, he first observed the lacteal vessels as a congeries of white cords disseminated through the mesentery; and on opening one of them with the point of the scalpel, the milky chyle flowed out, and the dis covery of the absorbent vessels was accomplished. Before that period the mesenteric veins were supposed, as in the time of Galen, to collect from the intestines all the nutritious products of digestion and to carry them to the liver, where they were worked up into the perfected blood, and the blood thence disseminated, through the rest of the venous system, outward to the whole body. A part of the blood only, passing to the heart and lungs, was thought to be arterialized, and so sent out through the arteries from the left ventricle, as the venous blood was sent out through the veins. The discovery of Aselli consisted simply in finding a new set of mesenteric vessels which took up from the intestines the chyle alone, and conveyed it toward the central organs.

He did not detect their real ultimate course, but supposed them to terminate in the liver, which still remained the supposed organ for the elaboration and perfection of the blood. It was only some years later (see Pecquet) that the independent course of the lacteals and lymphatics was ascertained, passing through the receptaculum chyli and the thoracic duct to the left subclavian vein. Aselli, however, was the pioneer in this discovery, and the subsequent success of others depended on the facts demonstrated by him. They are embodied in his dissertation De Lactibus sue Lacteis Venis (Milan, 1627).