38 PATHFINDER OF PHYSIOLOGY 



the animal body never manufactured any of these three compounds, 

 that all or any of them present in the animal body had been taken into 

 it with its food. 



Such was the current belief among physiologists of France at 



^ the beginning of the fourth decade of last century. The first heresy 



was uttered by Liebig who proved that the fat accumulated in the 



bodies of fattened geese exceeded greatly the quantity of fat in the 



intake of food, and furthermore that when a cow was fattened, the 



excreta during the fattening period contained as much fat as the food 



taken. At this time Bernard undertook his researches on the physi- 



r* ology of sugar. His first discovery was that cane sugar acted upQn 



\ by the gastric juice was changed into dextrose (glucose). It was his 



2 intention to study the tliree great claisses of foods, but he found it nec- 



j essary to confine his attention to the carbohydrates owing to the fas- 



/ cinating problems suggested by diabetes. He set about to discover the 



Vcause of the excess of sugar in diabetes with the hope of finding a 



remedy for the disease. 



Having previously satisfied himself that no dextrose was present 



; in the alimentary canal, or in the portal blood, Bernard fed a dog on 



meat only; killing the animal at the height of digestion he found to 



his great astonishment the blood loaded with dextrose. 



rv "Why!" said he, "if I have made no mistakes I have in this ex- 



S periment come upon the production of sugar; the liver produces sugar. 



^If the result I have got is confirmed on repetition of the experiment, 



the liver is the sugar-producing tissue. It manufactures sugar out 



of something that is not sugar, and within it lies the secret of dia- 



i betes. This is a big thing of which I have got hold. I must make 



// sure that I have made no mistake in the experiment, and then push 



^/ forward as far as possible the lead thus given me." 



C Bernard's results were confirmed by numerous experiments. He 



\ determined that the sugar in question was dextrose, responding to all 



' j the tests for dextrose. He also discovered that while this hepatic 



/ sugar did not come direct from the food, it was influenced in regard 



J to its quantity by the nature of the food. Starling , however, main- 



/ tains that in some animals, the carnivora, tne liver can continue to 



/ supply sugar to the blood on a diet which includes only proteins and 



I fats. Y an Noorden e xplains the fact that proteins yield sugar, by 



V the presence of a carbohydrate group in the protein molecule, which is 



split off during pepsin-hydrochloric acid digestion. 



Bernard eventually came to the conclusion that sugar was not 



formed immediately from the elements whatever they might be which 



the blood brought to the liver, but from some substance existing in 



the liver tissue which was capable of being converted into sugar...J[]j 



1857 he announced^iQ, the -scie ntific world the dis cDverv of gl ycog en. 



* Though he made known each step in his discoveries which extended 



•p over a number of years, he had the satisfaction of telling the whole 



j^ story in his own writings, never having experienced the humiliation 



which is sometimes the lot of pioneers, in seeing their leading con- 



,^ ceptions worked out by other minds. To ^uote liia^,IiiiQgxaph^^^lr 



C Michael Poster, "Bernard in the matter of glycogen not onlylaidThe 



J first stone but left a house so nearly finished that other men have been 



^ able to add but little." 



