THE PONS VAROLII. 519 



It would appear that much of the reflecting power of 

 the medulla oblongata may be destroyed; and yet its 

 power in the respiratory movements may remain. Thus, 

 in patients completely affected with chloroform, the wink- 

 ing of the eye-lids ceases, and irritation of the pharynx 

 will not produce the usual movements of swallowing, or 

 the closure of the glottis (so that blood may run quietly 

 into the stomach, or even into the lungs) ; yet, with all 

 this, they may breathe steadily, and show that the power 

 of the medulla oblongata to combine in action all the 

 nerves of the respiratory muscles is perfect. 



In addition to its influence over the functions of respi- 

 ration and deglutition, the medulla oblongata appears to be 

 largely concerned also in the faculty of speech. Schroeder 

 Yan der Kolk has especially developed this view, and 

 brought forward much evidence to prove that the corpora 

 olivaria are accessory ganglia, the main use of which is to 

 communicate simultaneously to the hypoglossal nerves the 

 multitudinous combinations of muscular movements re- 

 quired in speech, and thus to produce a uniform action of 

 both sides of the tongue. 



STRUCTURE AND PHYSIOLOGY OF THE PONS YAROLII, CRURA 

 CEREBRI, CORPORA QUADRIGEMINA, CORPORA GENICULATA, 

 OPTIC THALMI, AND CORPORA STRIATA. 



Pom Varolii. The meso-cephalon, or pons (YI, fig. 138), 

 is composed principally of transverse fibres connecting the 

 two hemispheres of the cerebellum, and forming its prin- 

 cipal commissure. But it includes, interlacing with these, 

 numerous longitudinal fibres which connect the medulla 

 oblongata with the cerebrum, and transverse fibres which 

 connect it with the cerebellum. Among the fasciculi of 

 nerve-fibres by which these several parts are connected, 

 the pons also contains abundant grey or vesicular sub- 



