452 GLOSSARY 



Sa-pon-i-fi-ca'tion (Lat. sapo, soap, and facer e, to make), the process 

 of making soap. Commonly the name soap is applied only to the 

 combination of soda or potash with the acid part of fat. But lime, 

 or magnesium, or other metal may take the place of soda or potash, 

 as it does when hard water and soap are used to wash the hands. 

 The lime soap which is formed feels sticky and rough, and does not 

 dissolve in water, but forms a white scum on the surface. 



Scap-u-la (Lat. scapulae, the shoulder blades), the flat bone upon the 

 back behind the shoulder. The shoulder blade. 



Sciatica (si-at'i-kd) (Gr. ischiadikos, pertaining to the hip), a painful 

 inflammation of the main nerve of the leg which begins just behind 

 the hip joint. 



Sclerotic (skler-ot'tc} (Gr. skleros, hard), the tough outer covering of 

 the eyeball. 



Scur'vy, the disease caused by lack of variety of food. It consists of 

 pain and of bleeding under the skin, especially of the legs and gums. 



Sebaceous glands (se-ba 1 'skits) (Lat. sebum, fat), the glands in the skin 

 which secrete oil. 



Se-cre'tion (Lat. secretus, separated), a substance which is separated 

 from the blood by the epithelium of glands and used by the body. 



Sem-i-cir'cu-lar canals, the three tunnels in the inner ear in which there 

 are nerves whose duty is to take note of the position of the body in 

 balancing itself. 



Sem-i-lu'nar valves, three half-moon-shaped valves at the beginning 

 both of the aorta and of the pulmonary artery. They prevent blood 

 from flowing back to the heart. 



Sen-sa'tion (Lat. sentire, to feel), a conscious impression made upon 

 the brain by an impulse brought by a sensory nerve. 



Sen'so-ry nerves (Lat. sentire, to feel), nerves which carry impulses 

 from the cells to the central nervous system. 



Se'rous membrane, the thin membrane lining the cavities of the body 

 which do not connect with its surface. It is named from the fluid, 

 like serum, which forms in it in a quantity just sufficient for lubri- 

 cation. 



Se'rum (Lat. serum, the watery part of curdled milk), the straw-colored 

 liquid which separates from a blood clot. 



Sewer (su'er), an underground tunnel for carrying slops from the houses 

 of a town. 



Si'nus (Lat. sinus, curve), a cavity. 



