GLOSSARY. 183 



Reflex action. The phenomena caused by a ganglion cell 



reflecting an afferent or centripetal impulse along an 



efferent or centrifugal nerve. 

 Refrac'tion (L. re, again ; frango, I break). The bending or 



alteration of direction which rays of light undergo when 



passing obliquely from one medium to another of differing 



density. 

 Reisner's membrane. A structure of the cochlea which 



separates scala vestibuli from canal of cochlea. 

 Remak's ganglion. The ganglion of sinus venosus. 

 Rennet. Milk curdling ferment. An extract of the fourth 



stomach of calf. 

 Reserve air. Also called supplemental. That air which can 



be forcibly expired after tidal air has left the chest. 

 Residual air. The air which remains in the lungs after the 



fullest expiratory effort. 

 Rhe'ocord (Gr. rheo, I flow; corda, a cord). An instrument 



for graduating the intensity of an electric current. 

 Rhe'ophore (Gr. rheo, I flow). The terminal of an electrical 



conductor. 

 Rheoscop'ic frog (Gr. rhed, I flow; scopeo^ I look into). An 



arrangement whereby the variations in the electrical 



currents of one muscle of a frog excite the nerve of another. 

 Rhodop'sin (Gr. \hodon^ a rose; ops, visual). The visual 



purple, or pigment found in outer limbs of retinal rods in 



most Vertebrates. 

 Ri'gor calo'ris (Gr. rtgeo, to be cold; calor^ ealoris, heat). 



A condition of muscle induced by exposure to high 



temperature, in which plasma coagulates and myosin is 



formed. 

 Ritter-Valli law. On disconnecting a nerve from its centre, 



irritability is increased at central end and proceeds 



towards periphery ; it afterwards diminishes in the same 

 ' direction. 

 Rivini, Notch of A space in the tympanic ring or groove 



which is filled in by the membrana flaccida or Shrapnell's 



membrane. 

 Rosenmuller's fossa. A depression close to pharyngeal 



orifice of Eustachian tube. 



Santorini, Cartilages of. Small nodules of elastic cartilage 

 situated in aryteno-epiglottic folds. 



