28 



whilst his communication was being written, there were none of these 

 disturbing circumstances. In a healthy dog, during a period of diges- 

 tion, the crura cerebri were completely divided. The animal was 

 thereby thrown into a state of unconsciousness, but breathed efficiently 

 of its own accord. The urine in an hour and a quarter's time was 

 found perfectly free from sugar. 



After poisoning by strychnine, the effect is the same as after de- 

 struction of the medulla oblongata. The circulation being maintained 

 by artificial respiration, the urine becomes strongly saccharine. 



Looking to these facts, and to the effect of Bernard's puncture of 

 the fourth ventricle in producing diabetes, the author is led to regard 

 the medulla oblongata as a centre, either directly presiding over the 

 functional activity of the liver, or indirectly affecting it by altering 

 through the medium of another or other organs the condition of the 

 blood going to it ; and he has endeavoured to establish upon positive 

 grounds the channel by which the propagation of the nervous influ- 

 ence may take place. It was this line of research that conducted to 

 the discovery of the strongly diabetic effect produced by dividing- 

 certain parts of the sympathetic. 



The medulla oblongata being thus presumed to form a centre 

 giving to the liver a force which prevents the saccharine" metamor- 

 phosis of its hepatine, experiment had already shown that it cannot be 

 through the spinal cord or the pneumogastrics separately, that the 

 transmission of nervous influence takes place. But an experiment was 

 performed to determine the effect of dividing both the spinal cord and 

 the two pneumogastrics together. The cord was crushed between the 

 third and fourth cervical vertebrae, and about half an inch of each 

 pneumogastric was cut away from the centre of the neck. Artificial 

 respiration was performed to keep up the circulation. The urine 

 remained entirely free from sugar, and the liver was found in an 

 exsaccharine state at the moment of discontinuing the respiration, 

 and became strongly saccharine afterwards. 



On next dividing all the nerves in the neck, an operation effected 

 by performing decapitation, the result that followed after three 

 quarters of an hour's artificial respiration was strongly saccharine 

 urine. After this experiment, and that of division of the spinal cord and 

 pneumogastrics, reason was afforded for looking to the sympathetic ; 

 and from the experiments that have been made and are described, 



