NATURE AND CAUSATION. 323 



perverted gastric and intestinal digestion, the blood being, it 

 was thought, directly charged with the material by absorption 

 from the alimentary canal, where its presence was accounted 

 for from imperfect elaboration of starchy and saccharine 

 matters. Further investigation, however, and particularly the 

 elaborate experiments of M. C. Bernard with regard to the 

 functions of the liver, have caused a partial abandonment, or 

 modification at least, of this theory. By these experiments, 

 Bernard sought to prove that one of the functions of the liver 

 was the secretion of a substance which, if not in itself sugar, 

 was at least converted into a saccharine material on meeting 

 some peculiar ferment of the blood in the hepatic veins. 

 Further, that in health, sugar was only found in the blood 

 circulating between the liver and the lungs ; that at the latter 

 organs, on meeting with the oxygen of the inspired air, it was 

 chemically changed. This chemical change or combustion, it 

 is now thought, is also extensively carried out at the peri- 

 pheral capillaries in the muscles, largely contributing to force- 

 production. 



In this way it has been attempted to be proved that the 

 presence of sugar in the general circulation, and its excretion 

 with the urine, must be due either to excessive hepatic or 

 defective pulmonary action. 



In addition, these experimental inquiries tended to show 

 that this peculiar excretory function of the liver was largely 

 modified by nervous action. 



The exciting agent of nervous influence in this hepatic 

 secretion Bernard believed to be the inspired air acting on the 

 pulmonary ramifications of the pneumogastric nerve, by which 

 it was transmitted to the brain, and from this organ by reflex 

 action along the spinal cord and splanchnic divisions of the 

 sympathetic to the liver. With as much if not greater ap- 

 pearance of truth, the nervous influence inducing this hepatic 

 secretion may be looked for as originating in the liver itself, 

 from stimulus supplied to the portal ramifications of the pneu- 

 mogastric, through medium of blood in the portal veins. This 

 seems the more feasible if saccharine diabetes be looked upon 

 as originally only a very peculiar form of dyspepsia, and seeing 

 also that it is most successfully combated on dietetic prin- 

 ciples. 



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