Bit. Mitchell on the Occurrence of Sur/ar in the Animal Economy. 87 



This leads us directly to suspect that the occurrence of sugar in the 

 animal economy, is more or less unconnected with the use of the saccha- 

 rine aliments. And what is here simply hinted at, I shall now adduce 

 experiments to prove. 



1st Experiment. — A rabbit was fed for several days on a mixture of 

 potatoes, starch, and carrots, it was then killed instantaneously, and blood 

 drawn from the right side of the heart. This was laid aside for coagula- 

 tion, which was found complete in about one hour. The serum, which 

 was alkaline, was then examined, and I determined in it the presence of 

 sugar in a manner the most positive. 



The stomach and small intestine also contained sugar, and traces of 

 starch unaltered. 



The urine was turbid, alkaline, and contained no sugar. 



2d Ex2oeri7nent. — A full grown rabbit was kept without food for two 

 days and then killed. The chest was at once opened, and the blood from 

 the right side of the heart collected in considerable quantity. In less than 

 an hour coagulation was complete, and the serum, clear and alcaline, gave 

 palpable indications of the presence of sugar. 



The stomach and small intestine were perfectly empty, and of course 

 contained no sugar. 



The urine, which prolonged abstinence as usual had rendered acid, was 

 likewise void of sugar. 



Zd Experiment. — A dog was allowed to fast for a couple of days, and 

 then put for a week on a diet wholly exempt from saccharine or feculent 

 matters. After this, while in full digestion, he was bled from the right 

 side of the heart. On subjecting the serum, which had completely separ- 

 ated from the clot in about three quarters of an hour, to the usual 

 re-agents, I had not the slightest difficulty in detecting the presence of 

 sugar. 



I then made infusions of the contents of the stomach and of the 

 chymous mass fi-om the small intestine, but in neither could I find evidence 

 of the existence of sugar. 



The same result, negative of the presence of sugar, followed the 

 examination of the urine. The urine gave an acid re-action with litmus 

 paper, as also did the infusions above referred to. 



I have repeated these experiments, and varied the manner of perform- 

 ing them, but without afi'ecting the result, and the same has been the 

 case in the hands of other observers. 



There can be little hesitation, therefore, in at once drawing the con- 

 clusion, to which they so naturally and necessarily lead us, viz. that the 

 occurrence of sugar in the blood of animals is constant and without refer- 

 ence to diet. 



One animal was fed on non-azotised food, a second was fed on azotised, 

 a third was subjected to compjlete ahstinence, and in all three sugar was 

 eqiujJly detected in the blood. I say wc cannot but arrive at one con- 

 clusion — the necessary deduction from these facts — " That sugar exists 



