4i8 Veteri7iary Medicine. 



pricking the floor of the fourth ventricle in the median Hne just 

 in front of the calamus scriptorius and near the root of the vagus 

 nerve, or a few ni'llimeters in front of this. 



It follows that irritation of this part of the medulla however 

 produced, whether from local disease, or b}' reflex action from 

 some distant organ in a state of irritation, ma}^ serve as the start- 

 ing point of diabetes in particular instances. That the cause ma}'' 

 be a reflex stimulus is shown by the suspension of the glj'cogenic 

 function after section of the vagus nerves, and its reappearance 

 when the central end of the cut vagus is galvanized, or, the floor 

 of the fourth ventricle is irritated, the direct or efferent excitation 

 being transmitted through the sympathetic nerve (Bernard). 

 I can cite a case of glycosuria in a man supervening on a severe 

 blow on the head from a falling ledger. Brain injuries which 

 suspend animal functions, but not the nutritive ones, such as 

 apoplexy, concus.sion of the brain or curare poisoning are liable 

 to induce diabetes. 



Traumatic injuries to other parts of the nervous system induce 

 glycosuria. Thus traumatism of the optic thalami ; of the cere- 

 bral lobes or peduncles ; of the pons ; of the cerebellum or of its 

 middle or posterior peduncles ; transverse section of the medulla 

 or of the .spinal cord opposite the second dorsal vertebra ; trauma- 

 tism of the superior or inferior cervical ganglion or the first 

 thoracic (Eckhard); of the sympathetic twig which accompanies 

 the vertebral artery (Pavy^); of the brachial plexus ; of the solar 

 plexus (Munck, Klebs); or of the sciatic nerve (Scliiff). 



The explanation of these facts may be sought in a reflex action 

 established by the conveyances of irritation to the true glycogenic 

 centres in the brain and the transference of the efferent nervous 

 impulse through the sympathetic nerve to the liver. It will be 

 borne in mind that in the case of section of the vagus nerve 

 electric .stimulation of its detatched peripheral part has no glyco- 

 genic effect on the liver, while galvanizing the central portion 

 determines gl3^cosuria. 



In the case of glj^cosuria through stimulation of the sympa- 

 thetic nerve or its ganglia the action may be concluded to be 

 direct. Strangely enough, irritation of the sympathetic between 

 the tenth and twelfth ribs or the splanchnic nerves fails to produce 

 glycosuria, though the hepatic branches of the sympathetic pass 

 through them. 



