CLAUDE BERNARD 57* 



and absorbed much lower down than was the case when it was fed to 

 dogs, and soon found that the variation was due to the different points 

 of entrance of the pancreatic duct into the intestine in the two animals. 

 This led to a long series of experiments on the function and properties 

 of the pancreas. He showed for the first time that the pancreas and not 

 the stomach was the chief organ of digestion and that the gastric juice 

 merely started the digestion which was completed by the more powerful 

 pancreatic juice. Its three-fold function for digesting proteins, fats 

 and carbohydrates was also demonstrated. For this work, which was 

 reported in 1848-9 and published complete in 1856, Bernard was 

 awarded the prize of experimental physiology by the Academie des 

 Sciences and was introduced to the scientific world as a physiologist of 

 remarkable ability and great promise. 



The story of the discovery of glycogen, which revolutionized prev- 

 alent biological theories concerning functions of the organs and differ- 

 ences between plant and animal metabolism, is interesting in showing 

 how a quick, alert mind can " grasp the hints that Nature gives " and 

 advance, step by step, to a final realization of the complete truth. 



The prevalent view concerning the differences between plant and 

 animal metabolism had been proposed by Dumas, the chemist, and 

 Boussingault, the agronomist. They showed that plants build up com- 

 plex organic compounds from inorganic substances and animals, by 

 feeding, take the complex compounds already formed and break them 

 down to simpler ones. Animals might modify them, but never make 

 them more complex. There was a complete cycle in which compounds 

 were built up by plants and broken down by animals. While this was 

 the prevalent view, there were some strong minds who opposed it. 

 Liebig confirmed Huber's old observation that bees, fed on sugar alone, 

 produce wax and showed that fattening geese accumulate fat in excess 

 of the fat fed. 



Bernard proposed to trace the successive steps by which the various 

 food-stuffs are transformed in the body and chose sugar as the subject 

 for his first investigation because it seemed liable to the simplest 

 explanation. The other foodstuffs were never investigated. He was 

 early interested in diabetes and wished to find the cause for the excess 

 of sugar in the blood and thereby assist in working out a remedy. His 

 plan was as follows : 



He had shown that cane sugar must be changed before it can be 

 retained by the blood. Tiedemann and Gmelin had proved that starch 

 is changed to sugar before it is absorbed from the alimentary tract. 

 This indicated to him that all carbohydrates enter the blood as simple 

 sugars. Where was this sugar destroyed ? If he could find the tissues 

 that caused the destruction and by some means decrease their activity, 

 the blood would become overloaded with sugar and experimental dia- 



