136 PHYSIOLOGY CHAP. 



yielded very divergent results, especially as regards the influence 

 of the various foods ingested. Heidenhain recognised these dis- 

 crepancies, but held to the opinion that the secretion of bile not 

 only increases during digestion, but exhibits two rises during this 

 period, one 3-5 hours, the other 13-15 hours after a meal. Not 

 being satisfied with these results, which differed from those 

 obtained by Spiro with Ludwig, we advised Baldi in 1881 to 

 repeat the same experiments in our laboratory, on dogs with a 

 complete biliary fistula, when they had quite recovered from the 

 operation and were in good physiological condition. He found a 

 surprising irregularity in the flow of the bile secretion, and was 

 unable to show any constant influence of digestion in general, or 

 of the nature of the foods administered to the animals. 



On comparing the quantity of bile secreted in the space of a. 

 few hours before and after a meal, he obtained a certain increase 

 during the period of digestion ; but the difference was not very 

 conspicuous, and may be interpreted as the effect rather of 

 increased blood-supply during digestion than of secretory excita- 

 tion of the hepatic cells. The entirely negative results obtained 

 with the so-called cholagogues (podophyllin, rhubarb, jalap, pilo- 

 carpine, aloe, etc.), in comparison with the immediate and con- 

 spicuous increase of the biliary secretion observed after injecting 

 ox bile, caused Baldi to revive the ancient doctrine of Aristotle, 

 Galen, and Morgagni, according to which the bile is a complex of 

 the products excreted by other tissues, the hepatic cells being only 

 the instruments of their selective elimination, as the cells of the 

 renal canaliculi are for the urinary products. 



Later work has shown this position to be untenable; but it 

 was certainly owing to Baldi's experiments that attention was 

 once more directed to this important problem. 



With regard to the process of bile secretion and the influence 

 exerted on it by various foods, Barbara's results (in a series of 

 publications, 1894-98, which sum up the methodical researches he 

 made in Albertoni's laboratory) are particularly interesting. 



Barbera carried out a number of comparative experiments 

 under identical conditions on dogs with a complete biliary fistula, 

 healed some time previously (at least four months) from the opera- 

 tion, when they had regained their initial body -weight, and 

 were accustomed to remain quietly in a Cyon's holder. The 

 day before each experiment, the dogs received a scanty meal of 

 mixed food, which was always identical in quality and quantity. 

 Twenty-four hours after, the animal was fixed to Cyon's holder, 

 and about three hours after fixation received the test meal, which 

 varied in its nature in different experiments on the same animal. 

 By this mode of procedure, it was possible to avoid any influence 

 of the preceding meal on the flow of secretion, while the effect of 

 the test meal was, fully brought out. 



