ligature, and the swelling of the distended duct below the ligature, broke down my doubt--_Ergo subducto paulo infra Claviculas vinculo, cum a ligaturâ sursum flaccesceret, superstite deorsum turgentis alveoli tumore, dubium meum penitus enervavit.... Laxatis vinculis, lacteus utrinque rivulus in Cavam affatim Chylum profudit._" It is to be noted that Asellius and Pecquet, both of them, made their discoveries as it were by chance. Unless digestion were going on, the lacteals would be empty and invisible; and, on the dead body, lacteals, receptaculum, and thoracic duct would all be empty. For these reasons, it cost a vast number of experiments to prove the existence, and to discover the course, of these vessels. Once found in living animals, they could be injected and dissected in the dead body; but they had been overlooked by Vesalius and the men of his time. From the discovery of the lacteals came the discovery of the whole lymphatic system. Daremberg, in his _Histoire des Sciences Médicales_ (Paris, 1870), after an account of Pecquet's work, says:-- "Up to this point, we have seen English, Italians, and French working together, with more or less success and genius, to trace the true ways of blood and chyle: there is yet one field of work to open up, the lymphatics of the body. The chief honour here belongs, without doubt, to the Swede Rudbeck, though the Dane Bartholin has disputed it with him, with equal acrimony and injustice." Rudbeck's work (1651-54) coincides exactly, in point of time, with the first and second editions, 1651 and 1654, of Pecquet's _De Lactibus_. It may be said, therefore, that the whole doctrine of the lymphatic system was roughed out half-way through the seventeenth century. III THE GASTRIC JUICE From many causes, the experimental study of the digestive processes came later than the study of the circulation. As an object of speculative thought, digestion was a lower phase of life, the work of crass spirits, less noble than the blood; from the point of view of science, it could not be studied ahead of organic chemistry, and got no help from any other sort of knowledge; and, from the medical point of view, it was the final result of many unknown internal forces that could not be observed or estimated either in life or after death. It did not, like the circulation, centre itself round one problem; it could not be focussed by the work of one man. For these reasons, and especially because of its absolute dependence on chemistry for the interpretation of its facts, it had to bide its time; and Réaumur's experiments are separated from the publication of Harvey's _De Motu Cordis et Sanguinis_ by a hundred and thirty years. The following account of the first experiments on digestion is taken from Claude Bernard's _Physiologie Opératoire_, 1879:--