88 Dr. Mitchell on the Occurrence of Sugar in the Animal Economy. 



constantly in the blood, whether the anmial have used a saccharine diet, 

 an animal diet, or have been subjected to abstinence from food of all sorts." 



In the case of the animal forming the subject of the first experiment, 

 the sugar detected in the alimentary canal and stomach might be, and 

 probably was, the source of that found in the blood ; but the same cannot 

 be the case with the animal which was fed entirely on nitrogenised food, and 

 whose intestine contained not a trace of sugar; and still less so with the 

 animal which had been subjected to prolonged abstinence, and whose 

 stomach and intestinal canal were perfectly empty. 



Whence then, it is naturally asked, came the sugar which existed in 

 the blood of the animals which were nourished on flesh, or denied food 

 altogether ? Such is the interesting question which I now proceed, as 

 far as possible, to determine. You have observed that it was invariably 

 found in the blood from the right side of the heart ; here, however, it 

 could not have been formed, but must simply have been transported to it 

 from some more or less distant organ. To discover this source, the 

 following experiments were instituted : — 



\st Experiment. — An adult and healthy dog, having made a copious 

 repast on cooked flesh, was killed seven hours afterwards. On opening 

 the abdomen the phenomena of active digestion were observed. The 

 following were laid aside for examination, viz.: — 1st, A portion of the 

 matters contained in the stomach and small intestine. 2d, Some chyle 

 from the thoracic duct. 3d, Blood from the portal vein, by an incision 

 near the point where the splenic vein joins it. And, 4th, Blood from the 

 right side of the heart. 



1st, In the contents of the stomach and small intestine no trace of 

 sugar existed. Both were acid. 



2d, The serum of the chyle from the thoracic duct was alkaline, but 

 gave no indications of the presence of sugar. 



3d, The scrum of the blood from the portal vein was slightly lactescent 

 and alkaline, and contained sugar in great abundance. 



4th, The blood from the right ventricle of the heart presented a serum 

 also milky and alkaline, and giving indications of the presence of sugar, 

 but in much smaller quantity than in the blood from the portal vein. 



2d Experiment A healthy and adult dog was killed on the third day 



of a total abstinence from food of all sorts. On opening the abdomen, 

 such phenomena were observed as always accompany the inactivity of the 

 digestive organs ; a paleness and anaemia of all the organs, with vacuity 

 and retraction of the stomach and intestines. The thoracic duct contained 

 a chyle or lymph, which was transparent, or very slightly opalescent. 



1. In the first place, blood from the trunk of the portal vein was 

 examined. The serum which separated was limpid and alkaline, and 

 contained evident proofs of the presence of sugar, although certainly in 

 less quantity than in the former experiment. 



2. The blood from the right ventricle was then subjected to the usual 

 re-agents, and gave indubitable proof of its containing sugar. 



