ABSORPTION BY LACTEAL AND LYMPHATIC VESSELS. 423 



than in a physiological point of view. Our knowledge of 

 the anatomy of the absorbent system dates from the discov- 

 ery of the thoracic duct; but from the discovery of the lac- 

 teals, dates the history of these vessels as the carriers of 

 nutritive matters from the intestinal canal to the general 

 system. 



In 1622, in making an experiment on a dog for the pur- 

 pose of demonstrating to some scientific friends certain points 

 connected with the functions of the recurrent laryngeal 

 nerves, Asellius opened the abdomen and saw for the first 

 time little white vessels passing back from the intestine 

 between the folds of the mesentery. Not knowing at first 

 the nature of these vessels, he punctured one of them, and 

 the milky fluid escaped, revealing their true character. 1 

 The discovery of the lacteal system was thus made appar- 

 ently by pure accident. The entire history of this discovery 

 is given by its author. He states that when the dog died, 

 the white vessels disappeared from before his eyes. The fol- 

 lowing day, on opening the abdomen of another dog, he 

 found no lacteals ; but remembering that the first animal 

 had been experimented upon while in full digestion, he ex- 

 posed the abdominal organs in another dog under the same 

 conditions, and again found the vessels full of chyle. His 

 observations upon dogs were afterward confirmed by experi- 

 ments upon cats, sheep, and many other animals. Asellius 

 died in 1626, and it was reserved for others to complete his 

 discovery by showing the true course of the lacteals ; he 

 supposing that they passed directly to the liver, where the 

 chyle was made into blood. His* work, De Lactibus sive 

 Lacteis Venis, was published in 1628, 2 by Tadinus and Sep- 



1 GASPAR ASELLIUS, De Ladibus sive Lacteis Venis, etc., Basilese, Typis Henric- 

 Petrinis, 1628, p. 19 et seq. 



*' J The copy of Asellius in our possession was published by Alexander Tadinus 

 and Senator Septalius, and bears the date of 1628. Reference to the same work, 

 published in 1627, at Mediol, is made by Berard ( Cours dc Physiologic, Paris, 

 1849, tome ii., p. 563). 



