THE PONS VAEOLII AND ORURA CEREBRT. 119 



What other important functions are supposed to belong to the 

 gray matter of the medulla ? 



The origin of the roots of certain of the cranial nerves here has 

 caused the special senses of hearing and of taste to be referred to this 

 region ; and the connection with the sympathetic system through the 

 cord has caused the centre for the dilatation of the pupil to be located 

 in the medulla. Phonation is also dependent upon the action of 

 nerves arising in this focus of gray matter, and no voluntary or 

 reflex sound can be produced by an animal in which the speech- 

 centre in the medulla is destroyed. The origin here of the hypo- 

 glossal and pneumogastric nerves, involving as they do the move- 

 ments of the tongue and glottis, controls both the acts of phonation 

 and articulation. 



What is glosso-labio-laryngeal paralysis? 



It is a progressive degeneration of the gray matter of the me- 

 dulla, and it shows itself first in a paralysis of the tongue, which 

 renders articulation of certain sounds indistinct : as the degenera- 

 tion progresses in the medulla the articulation becomes more and 

 more impossible and deglutition is affected. The disease continues 

 to affect more and more of the functions dependent upon the me 

 dulla, until death ensues as a result of involvement of the cardiac 

 and respiratory centres or of inability to take food. It is some- 

 times called bulbar paralysis. 



With such varied and important powers, can the medulla be 



classed as an organ of the mind ? 



It cannot, for the reason that it has no voluntary control of any 

 of its powers. They are all reflex, or respond to volition originat- 

 ing elsewhere in the brain. Though the regulation of the action 

 of the heart and of the lungs is dependent upon the medulla, and 

 many other functions of absolute need may be given to it, yet its 

 power is not of a character to permit it to be called an organ of 

 the mind. 



THE PONS VAROLII AND CRURA OEREBBI. 

 What is the pons Varolii ? 



It is a collection of nervous tissue lying immediately above the 

 medulla. It consists of white fibres, with areas of gray matter 

 filling in the intervals between the fasciculi of white fibres. The 

 white fibres connect the brain with the medulla, and join the 



