326 



SECRETION. 



allow the bladder to pass up above the point of pressure, 

 and it will be found turbid, alkaline, and without sugar. In 

 one or two hours after the operation, the urine will have be- 

 come clear, acid, and will react readily with any of the 

 copper-tests. "When this operation is performed without in- 

 juring the adjacent organs, the presence of sugar in the 

 urine is only temporary, and the next day, the secretion 



FIG. 14. 



Section of the head of a rabbit, showing the operation of puncturing the floor of the 

 fourth ventricle, a, cerebellum ; J, origin of the seventh pair of nerves ; c, spinal 

 cord ; d, origin of the pneumogastric ; e, opening of entrance of the instrument into 

 the cranium : /, instrument ; g, fifth pair of nerves ; A, auditory canal ; i, extremity 

 of the instrument on the spinal cord after having penetrated the cerebellum ; #, oc- 

 cipital venous sinus ; /, tubercula quadrigemina ; m, cerebrum ; n, section of the atlas. 

 (BERNARD, Lemons de physiologic experimental, Paris, 1855, p. 293.) 



will have returned to its normal condition. It is best, in 

 performing this experiment, to operate on an animal in full 

 digestion, when the production of sugar is at its maximum. 



The production of diabetes in this way, in animals, is 

 exceedingly interesting in its relations to certain cases of the 

 disease in the human subject, in which the affection is trau- 

 matic, and directly attributable to injury near the medulla. 



