310 SECRETION. 



It seems probable, in reflecting upon these facts, that, 

 inasmuch as no one has assumed that the actual quantity of 

 sugar produced by the liver is very considerable, and as a 

 large quantity of blood (in which the sugar is very soluble) 

 is constantly passing through the liver, precisely as we pass 

 water through its vessels to remove the sugar, the sugar 

 might be washed out by the blood as fast as it is formed ; 

 and really the liver might never contain sugar in its sub- 

 stance, as a physiological condition, although it is constantly 

 engaged in its production. We know that the characteristic 

 elements of the various secretions proper are produced in 

 the substance of the glands, and are washed out at the 

 proper time by liquid derived from the blood, which circu- 

 lates in their substance during their functional activity in 

 very much greater quantity than during the intervals of 

 secretion. ISTow, the liver-sugar may certainly be regarded 

 as an element of secretion ; and, possibly, it may be com- 

 pletely washed out of the liver, as fast as it is formed, by 

 the current of blood; the hepatic vein, in this regard, 

 serving as an excretory duct. 



To put this hypothesis to the test of experiment, it was 

 necessary to obtain and analyze a specimen of the liver in 

 a condition as near as possible to that under which it exists 

 in the living organism ; and in carrying out this idea, we 

 instituted the following experiments : 



Experiment I. A medium-sized dog, full grown, in 

 good condition, not in digestion, was held upon the operat- 

 ing-table by two assistants, and the abdomen was widely 

 opened by a single sweep of the knife. A portion of the 

 liver, weighing about two ounces, was then excised and 

 immediately cut into small pieces, which were allowed to 

 fall into boiling water. The time from the first incision 

 until the liver was in the boiling water was twenty-eight 

 seconds. An excess of crystallized sulphate of soda was 

 then added, and the mixture was boiled for about five min- 

 utes. It was then thrown upon a filter, and the clear fluid 



