EXPERIMENTAL DIABETES 3^3 



and, furthermore, that this centre can be excited through several 

 sensory nerves. It remains for us to ascertain by what nerve 

 path the efferent impulses from this centre are transmitted, and 

 if it be the hepatic glycogen alone which is transformed into 

 sugar when the centre is stimulated, or whether glycogen stored 

 elsewhere in the organism may not also contribute. 



If the splanchnic nerves be cut just after their entry into the 

 abdomen, or the upper three thoracic nerve roots torn out, or 

 the spinal cord cut across above the first thoracic root, and the 

 diabetic centre be then punctured, no diabetes will be found to 

 result (Marc LafTont, 6 Eckhard 17 ). On the other hand, if the 

 spinal cord be irritated opposite the brachial swelling (Pavy 6 ), 

 or if the posterior columns alone be cut (SchifE 18 ), or if the lower 

 cervical and upper thoracic sympathetic ganglia be cut, a more 

 or less marked glycosuria will result independent of puncturing 

 the fourth ventricle. The cutting, in these experiments, doubtless 

 acts as an irritation. 



All these experiments are usually taken to show that the 

 efferent path of the impulses from the glycosuric centre is by the 

 spinal cord as far as the upper thoracic region, then by the upper 

 thoracic spinal roots and rami communicantes into the lower 

 csrvical and upper thoracic sympathetic ganglia, and then by the 

 splanchnic nerves to the liver. It is also concluded that it can be 

 the hepatic glycogen alone which is influenced by the glycosuric 

 centre, since, were the glycogen in the muscles, &c., also under its 

 control, glycosuria after puncture should not be inhibited by 

 cutting the splanchnics or upper thoracic nerve roots. 



As stated above, irritation of the cervical spinal cord, or of the 

 upper thoracic and lower cervical sympathetic ganglia, is followed 

 by glycosuria ; if, however, the splanchnic nerve be irritated 

 (electrically stimulated), no glycosuria is induced. This remarkable 

 result would seem to indicate that in passing through the sym- 

 pathetic ganglia, the glycosuria-producing impulses had undergone 

 some change; stimulation of the pre-ganglionic nerve fibre pro- 

 ducing glycosuria, which, however, is not produced by stimulating 

 the post-ganglionic. 



As is well known, Langley has shown that nicotin paralyses the 

 synapses of pre-ganglionic fibres in the sympathetic ganglia ; that 

 it institutes a block so that impulses can no longer pass through 

 the ganglia. Wishing, therefore, to see whether the glycosuria-pro- 



