ANATOMY AND PHYSIOLOGY OF THE BKAIN. 425 



could understand but could not articulate speech, and in 

 which examination after death revealed that these organs 

 were either altered by disease, or otherwise partially or 

 completely absent. This theory would seem further corro- 

 borated by the fact, that though in the domestic quadru- 

 peds two of these bodies exist on either side, they are so 

 rudimentary that veterinary anatomists have frequently 

 denied their existence. Both in man and in animals they 

 are connected with the nuclei of origin of the facial and 

 hypoglossal nerves. 



It is curious, as shown by Bernard, that the pricking of 

 the floor of the fourth ventricle, between the roots of the 

 eighth and tenth cranial nerves, causes diabetes mellitus 

 (secretion of sugar in the urine). If the pricking is made a 

 little higher, the secretion of urine is diminished, and it 

 becomes albuminous. If the puncture is made still more 

 forward, near the poiis, and close behind the root of the 

 trifacial nerve, it leads to a great increase of the salivary 

 secretion. 



The pons Varolii is the medium of connection between 

 the three other divisions of the brain, and, accordingly, 

 contains fibres from each of these parts. The difficulty 

 of experimenting upon this organ, from its position and its 

 proximity to other parts of the most vital importance to 

 life, and the numerous functions it possesses as a conduct- 

 ing agent, renders it extremely difficult or impossible to 

 ascertain its precise properties. Longet found that the 

 irritation of the inferior parts was not painful, but pro- 

 duced convulsions of the face, limbs, and other parts. 

 Interference with the posterior part, on the other hand, 

 produced lively suffering. Brown-Sequard infers, from the 

 analysis of cases in which this organ was diseased, that its 

 central part is the conductor of sensory impressions to 



