(b. Cremona, Italy, 1581; d. Milan, Italy, 9 September 1625)
A descendant of an ancient patrician family, Aselli revealed a marked propensity for the natural sciences early in his schooling. He studied medicine at the University of Pavia, where he soon distinguished himself among his fellow students. His teacher of anatomy was Giambattista Carcano-Leone, a pupil of Fallopio and author of De cordis vasorum in foetu unione (1574).
Later Aselli moved to Milan, where he gained recognition in his profession. Since his scientific preparation was essentially in anatomy, he distinguished himself in his practice of surgery. He was appointed first surgeon of the Spanish army in Italy from 1612 to 1620. In Milan he had the opportunity to continue his anatomical researches, which won him honorary citizenship of that city and an outstanding position in the history of anatomy. He died at the age of forty-four from an acute and malignant fever.
Aselli’s scientific activity occurred during the first decades of the seventeenth century, in an atmosphere that was particularly sympathetic to anatomical studies, especially in northern Italy. At the end of the sixteenth century the study of descriptive human anatomy had made considerable progress. The early decades of the seventeenth century felt the effects of the baroque attitude toward science and the influences of the new mechanical concepts of Galileo. Anatomy, which had been essentially static in the sixteenth century, now assumed a dynamic character. It was enlivened by a new consideration of physiology.
Aselli discovered the chylous vessels, although it would perhaps be more correct to refer to his work as a rediscovery rather than a discovery. According to information that has come down to us from Galen, Herophilus, and Erasistratus, both Hippocrates and Aristotle had with considerable clarity already pointed to the existence of the so-called absorbent vessels. Nevertheless, not even Eustachi and Fallopio, who in the sixteenth century had noted and described the thoracic duct in the horse and the deep lymphatics in the liver, respectively, had succeeded in clarifying the functional significance of these vessels.
On 23 July 1622, during a vivisection performed on a dog that had recently been fed, Aselli, in the course of removing the intestinal tangle to reveal the abdominal fasciae of the diaphragm, noticed numerous white filaments ramified throughout the entire mesentery and along the peritoneal surface of the intestine. The most obvious interpretation was that these filaments were nerves. The incision of one of the larger of these “nerves” released a whitish humor similar to milk. Therefore, Aselli interpreted these formations as a multitude of small vessels, proposing to call them “aut lacteal, sive albas venas.” The vivisection had been performed at the request of four of his friends, among whom were Senator Settala and Quirino Cnogler, to demonstrate the recurrent nerves and the movements of the diaphragm.
Immediately following his discovery, Aselli began a systematic study of the significance of these vascular structures. He recognized the chronological relationship that existed between their turgidity and the animal’s last meal. His experimental findings enabled Aselli to observe the chylous vessels in different species of animals. The results of these investigations were collected in De lactibus sive Lacteis venis quarto vasorum rnesaraicorurn genere novo invento Gasparis Asellii Cremonensis anatomici Ticinensis dissertatio (1627), which is divided into thirty-five chapters that are followed by an index and preceded by four charts with accompanying commentaries and a portrait of the author. Besides their intrinsic scientific value, the importance of the charts lies in the new technique used in composing them: they were the first anatomical illustrations to appear in color. Aselli used color because he felt ihat several tints were needed in order to distinguish the various types of vessels more clearly.
Aselli traced the course of the chylous vessels to the mesenteric glands and probably confused them with the lymphatics of the liver; therefore he did not follow their course to the thoracic duct. (His discovery occurred six years before the publication of Harvey’s De motu cordis, and so the Galenic concept of the liver as the center of the venous system still appeared valid.) Harvey himself believed that the absorption of the chyle took place through the mesenteric veins and that the liver generated the blood. With the discovery of the thoracic duct in the dog by Jean Pecquet in 1651, the old Galenic error, according to which the vessels of the intestine carried the chyle to the liver, was corrected. In addition to noting and describing the valvular apparatus of the chylous vessels, Aselli attempted to interpret their functional significance in health and in disease.
I. Original Works. Aselli’s only published work is De lactibus sine Lacteis venis quarto vasorum mesaraicortan genere novo invento Gasparis Asellii Crenionensis anatomici Ticinensis dissertatio (Milan, 1627; Basel, 1628; Leiden, 1640; Amsterdam, 1645), which was issued at the insistence of his friends Senator Settala and Alessandro Tadino.
Two earlier works by Aselli, De venenis and Observationes chirurgicae, are presumed lost. Two series of manuscripts are extant: the more important is preserved in the Archives of the Civic Museum of Pavia. In addition to other lectures and charts, it contains the full text of the lectures on the chylous vessels that Aselli delivered in 1625. The other series concerns the Observationes chirurgicae; formerly in the possession of the noble Belgioioso family, it was turned over in 1920 to the Trivulziana Library of Milan.
II. Secondary Literature. Writings on Aselli are F. Argelati, Bihlioteca scriptorum Mediolan (Milan, 1755), II, 2058; H. Boruttau, “Geschichte der Physiologic...,” in Theodor Puschmann’s Handbuch der Geschichte der Medizin, II (Jena, 1903), 335–336; C. A. Calderini, Storia della letteratura e delle arti in Italia (Milan, 1836). II. 379; P. Capparoni, Profili bio-bibliografici di medici e naturalisti celebri italiani dal sec. XV al sec. XVIII (Rome, 1928), II, 70–72; B. Corte, Notizie istoriche intorno a’ Medici Scritlori Milanesi (Milan, 1718), p. 176; V. Ducceschi, “I manoscritti di Gaspare Aselli,” in Archivio di storia delta scienza, 3 (1922), 125–134; J. F. Fulton, “The Early History of the Lymphatics,” in Bulletin of the Hennepin County Medical Society, 9 (1938), 5; J. I. Mangeti, Bibliotheca scriptorum medicorum (Geneva, 1731), I, 185; G. Mazzucchelli, Gli scrittori d’Italia (Brescia, 1753), I, part 2, 1159–1160; L. Premuda, Storia dell’i conografia anatomica (Milan, 1957), pp. 163–164; R. von Töply, “Geschichte der Anatomic,” in Puschmann’s Handbuch (supra), pp. 215–216; and G. Zoia, Cenno sulla vita di Gaspare Aselli anatomico del secolo XVII (Pavia, 1875).