362 GLOSSARY 



Pe'trous (Gr. irtrpa, petra, a rock). The name of the hard portion of the 

 temporal bone, in which is situated the drum of the ear and labyrinth. 



Phar'ynx (Gr. <f>dpvy, pharunx, the throat). The cavity between the 

 back of the mouth and gullet. 



Phys-i-ol'o-gy (Gr. 0vo-is, phusis, nature, and \67os, logos, a discourse). 

 The science of the functions of living, organized beings. 



Pi'a Ma'ter (L.) . Literally, the tender mother ; the innermost of the 

 three coverings of the brain. It is thin and delicate ; hence the name. 



Pleu'ra (Gr. ir\evpd, a rib). A membrane covering the lung and lining 

 the chest. There is one for each lung. 



Pleu'ri-sy. An inflammation affecting the pleura. 



Pneu-mo-gas'tric (Gr. irvev^wv, pneumon, the lungs, and yaar-rip, gaster, 

 the stomach). The name of a nerve distributed to the lungs and 

 stomach ; it is the principal nerve of respiration. 



Pneu-mo'ni-a (Gr.). An inflammation affecting the air-cells of the 

 lungs. 



Pres-by-o'pi-a (Gr. Trptafivs, presbus, old, and ty, ops, the eye). A defect 

 of the accommodation of the eye, caused by the hardening of the 

 crystalline lens ; the "far-sight" of adults and aged persons. 



Proc'ess (L. proce'do, proces'sus, to proceed, to go forth). Any projec- 

 tion from a surface. Also, a method of performance ; a procedure. 



Pty'a-lin (Gr. irrvaXov, ptualon, saliva). The peculiar organic ingre- 

 dient of the saliva. 



Pul'mo-na-ry (L. pul'mo, pulmo'nis, the lungs). Pertaining to the lungs. 



Pulse (L. pel'lo, pul'sum, to beat). The striking of an artery against 

 the finger, occasioned by the contraction of the heart, commonly felt 

 at the wrist. 



Pu'pil (L. pupil 1 la). The central, round opening in the iris, through 

 which light passes into the depths of the eye. 



Py-lo'rus (L. irv\ti)p6s, puloros, a gate-keeper). The lower opening of 

 the stomach, at the beginning of the small intestine. 



Re'flex Action. An involuntary action of the nervous system, by which 

 an external impression conducted by a sensory nerve is reflected, or 

 converted into a motor impulse. 



Res-pi-ra'tion (L. res'piro, to breathe frequently). The function of 

 breathing, comprising two acts : inspiration, or breathing in, and 

 expiration, or breathing out. 



Ret'i-na (L. re'te, a net). The innermost of the three tunics or coats of 

 the eyeball, being an expansion of the optic nerve. 



Sac'cha-rine (L. sac'charum, sugar). Of the nature of sugar; applied 

 to the important group of food substances which embraces the dif- 

 ferent varieties of sugar, starch, and gum. 



Sa-li'va (L.). The moisture or fluids of the mouth, secreted by the 

 salivary glands, etc. 



