Denis, Jean-Baptiste

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Denis, Jean-Baptiste

(b. Paris, France, 1640 [?]; d. Paris, 3 October 1704)


Denis was born in Paris, presumably in the 1640’s. He was the son of a hydraulic engineer who was Louis XIV’s chief engineer in charge of the works distributing the water of the Seine from the pumps at Marly to the fountains at Versailles.

Denis is said to have studied medicine at Montpellier (1), but no records of his inscription as a medical student or of the conferring upon him of a diploma as doctor in medicine can be found in the very complete archives of the Faculty of Medicine. Niceron says that he obtained “un bonnet de Docteur en cette Faculté” and that “il fut aggrégé à la Chambre Royale” (10). On the other hand, Martin de la Martinière, who was a physician in ordinary to the king, in a letter to Denis accuses him of taking the title of “maître” because of a “lettre de Médecine” that he obtained in Rheims (2). Nothing has yet been found in Rheims indicating that he obtained such a degree. While in Paris he taught philosophy and mathematics, assuming the title of professor, which he placed at the head of most of his works. No evidence for a degree in mathematics or philosophy has yet been found.

Beginning in 1664, Denis gave public lectures in physics, mathematics, and medicine at his home on the quai des Grands-Augustins in Paris, and published these lectures as conference reports (7). He also joined the group surrounding Habert de Montmort, which met to discuss the new philosophy much like the groups in London that preceded the Royal Society. When the Académie des Sciences was established in 1666, the Montmort group did not participate and continued its own meetings independently of that body.

The discovery of the circulation of blood by William Harvey stimulated experiments on the circulation; intravenous injection was begun by Christopher Wren and Clarke in the 1650’s. This was followed by the first trial of transfusion of blood in animals. After discussions at the Royal Society as early as its public meeting of 17 May 1665, an account of successful transfusion in dogs was given by Richard Lower in a letter written to Robert Boyle on 6 July 1665 and submitted by Boyle to the Royal Society. This led to another successful transfusion in November 1666 at the Royal Society (9).

When reports of these experiments reached Paris late in 1666 or early in 1667, the Académie des Sciences immediately set about repeating them, appointing a committee including Louis Gayant, an anatomist; Claude Perrault, the physician noted for the east facade (the Colonnade) of the Louvre; and Adrien Auzout, the astronomer. Gayant performed the first transfusion in Paris on 22 January 1667, using dogs. Transfusion also attracted the interest of the Montmort Academy, which apparently appointed Denis and Paul Emmerez, a surgeon from St.-Quentin, to carry out independent studies. On 3 March 1667 Denis performed a transfusion experiment on two dogs (8). On 2 April 1667 various experiments involving transfusion from three calves to three dogs were made. These were published in the Royal Society’s Philosophical Transactions (11).

But it was the transfusion of blood in men which was of the greatest interest to Denis, gave him his celebrity, and started the greatest medical controversy of that time. In these experiments he was assisted by Paul Emmerez.

The first transfusion of blood in man was made on 15 June 1667, on a drowsy and feverish young man. From a lamb he received about twelve ounces of blood, after which he “rapidly recovered from his lethargy, grew fatter and was an object of surprise and astonishment to all who knew him” (4).

The second transfusion was carried out on a fortyfive-year-old chair bearer, a robust man who received the blood of a sheep (4). He returned to work the next day as if nothing had happened to him.

The recipient of the third transfusion was Baron Bonde, a young Swedish nobleman who fell ill in Paris while making a grand tour of Europe. He was in such a bad state that he had been abandoned by his physicians; and in despair, having heard of Denis’s new cure, his family asked Denis to attempt transfusion of blood as a final recourse. After the first transfusion, which was from a calf, Bonde felt better and began to speak. This improvement lasted only a short time, however, and he died during a second transfusion.

The fourth transfusion patient was a madman, Antoine Mauroy (5), who died during a third transfusion. He may have been poisoned by his wife, who, perhaps to divert suspicion from herself or at the suggestion of the many Paris physicians antagonistic to Denis, accused Denis of having killed her husband. Denis brought the case before the court, and a judgment rendered on 17 April 1668 cleared him of any wrongdoing but forbade the practice of transfusion of blood in man without permission of the Paris Faculty of Medicine. Meanwhile, another transfusion had been made by Denis, on 10 February 1668, on a paralyzed woman. After this, however, the practice of transfusion faded out as suddenly as it had begun.

In 1673 Denis was invited to England by Charles II, who wished to learn about transfusion and other remedies purportedly discovered by Denis. He went to England and successfully treated the French ambassador and several personalities of the court. Despite offers to remain, he became dissatisfied and returned to Paris (10), where he continued his interest in science and mathematics (7) but never practiced medicine or again concerned himself with transfusion. He died suddenly on 3 October 1704.


1. Jean Astruc, Mémoires pour servir à l’histoire de la Faculté de Montpellier, rev. by M. Lorry and P. G. Cavelier, V (Paris, 1767), 378.

2. Martin de la Martinière, Remonstrances charitables du Sieur de la Martinière à Monsieur Denis (Paris, 1668).

3. J.-B. Denis, Lettre à M. L’Abbé Bourdelot... pour servir de réponse au Sr. Lamy et confirmer la transfusion du sang par de nouvelles expériences (Paris, 1667).

4. J.-B. Denis, Lettre escrite à... Montmor... touchant une nouvelle manière de guérir plusieurs maladies par la transfusion du sang, confirmée par deux expériences faites sur des hommes (Paris, 1667).

5. J.-B. Denis, Lettre escrite à M.... touchant une folie invétérée, qui a esté guérie depuis peu par la transfusion du sang (Paris, 1668).

6. J.-B, Denis, Lettre écrite à... Sorbière... touchant l’origine de la transfusion du sang, et la manière de la protiquer sur les hommes (Paris, 1668).

7. J.-B. Denis, Recueil des mémoires et conférences qui ont été présentées à Monseigneur le Dauphin pendant l’année 1672 (1673–1674), (Paris, 1672–1683).

8. J.-B. Denis, “Extrait d’une lettre de M. Denis, professeur de philosophic et de mathématique, sur la transfusion du sang. De Paris le 9. mars, 1667,” in Journal des sçavans, 6 (1679).

9. Minutes of the Royal Society (16 Sept. 1663), p. 201.

10. J. P. Niceron, Mémoires pour servir à l’histoire des hommes illustres de la république des lettres, XXXVII (Paris, 1727), 77.

11. “An extract of the letter of Mr. Denis... touching the transfusion of blood, of April 2. 1667,” in Philosophical Transactions of the Royal Society, 1 , no. 25 (6 May 1667), 453.

Hebbel E. Hoff