PRODUCTION OF SUGAR LIST THE LIVER. 325 



main results of some of the most striking of the experiments 

 on this subject. 



The most remarkable experiment upon 

 the influence of the nervous system on the 

 liver is the one in which artificial diabetes 

 is produced by irritation of the floor of the 

 fourth ventricle. This operation is not diffi- 

 cult, and is one that we have often repeated. 

 The instrument used is a delicate stilet, with 

 a flat cutting extremity, and a small project- 

 ing point, about -% of an inch long. 1 In per- 

 forming the operation upon a rabbit, the 

 head of the animal is firmly held in the left 

 hand, and the skull is penetrated in the 

 median line, just behind the superior occipi- 

 tal protuberance. This can easily be done 

 by a few lateral movements of the instrument. 

 Once within the cranium, the instrument is 

 passed obliquely downward and forward, so 

 as to cross an imaginary line between the 

 two auditory canals, until its point reaches 

 the basilar process of the occipital bone. The 

 point then penetrates the medulla oblongata, 

 between the roots of the auditory nerves and 

 the pneumogastrics, and, by its projection, 

 serves to protect the nervous centre from 

 more serious injury from the cutting edge. 

 The instrument is then carefully withdrawn, 



-, . .. . i ,L i a mi Instrument for pnnc- 



and the operation is completed. This ex- turin? the floor of 



. . , . -. -. . . . , , the fourth ventricle 



penment is almost painless, and it is not de- (BERNARD, Leyons 



, , , . . ,, , . de physiologie ex- 



sirable to administer an anaesthetic, as this, pfrtmaOate^ Pan?, 



1855, p. 290). 



in itself, would disturb the glycogenic pro- 

 cess. The urine may be drawn before the operation, by 

 pressing the lower part of the abdomen, taking care not to 



1 These instruments have been made by Messrs. Tiemann & Co., of this city. 



2 BERNARD, Lemons de physiologic experimentale, Paris, 1855, p. 291, et seq. 



