GLOSSARY 45 1 



Pulse (Lat. pulsus, a blow), the wave which may be felt in an artery 



with each heart beat. 

 Pu'pil (Lat. pupilla}, the opening in the iris through which light enters 



the eye. It appears as a round black spot in the center of the col- 

 ored part of the eye. 

 Pus (Lat. puteo, to rot), the creamy matter which flows from an abscess. 



It is formed mostly of dead white blood cells. 

 Pu-tre-fac'tion (Lat. putris, rotten, and facere, to make), the process 



of decay accompanied by bad odors. 

 Py-lo'rus (Gr. pule, a gate), the orifice in the right end of the stomach, 



through which food passes into the intestine. 

 Py'ri-dine (Gr. pur, fire), a poisonous substance formed by burning 



nicotine. 



Ra'di-us (Lat. radius, the spoke of a wheel), the bone upon the thumb 



side of the arm, below the elbow. 

 Re'flex action (Lat. re, back, and flectere, to turn), the action of the 



central nerve cells in sending orders for motion in response to 



an impulse brought by sensory nerves. 

 Ren'nin, a lifeless ferment extracted from the lining of the fourth 



stomach of a calf, and used to curdle milk in cheese making. 



The same ferment is found in the human stomach, especially in 



infancy. 

 Res-pi-ra'tion (Lat. re, again, and spirare, to breathe), the process of 



breathing and of the interchange of oxygen and carbonic acid gas 



in the cells of the body. 

 Ret'i-na (Lat. rete, a net), the inner lining of the eye in which the 



nerves of sight end. 



Rheumatism (ru 1 ma-tisni) (Gr. rheum, a flowing or stream), a swell- 

 ing of the joints in which they are often quickly affected one after 



another. Usually it is due to fluid collecting in the bag of the 



synovial membrane. 

 Rick'ets, a disease in which the bones have too little lime and bend too 



easily. 



Sa'crum (Lat. sacer, sacred, for the bone was offered in sacrifice), the 

 part of the backbone which completes the pelvis behind. 



Sa-li'va (Lat. saliva; Gr. sialon, spittle), the watery fluid in the 

 mouth. 



