340 



OUR BODIES AND HOW WE LIVE 



Pro'to-plasm (Gr. TrptDros, first, and 

 ir\a(r<reiv, to mold). The viscid 

 material constituting the essential 

 substance of living cells upon 

 'which all the vital functions of 

 the body depend. 



Pto'ma-ine (Gr. TrrtD/^a, a corpse). 

 One of a class of substances, re- 

 sembling the vegetable alkaloids, 

 formed during the decomposition 

 of proteids. See " Toxin." 



Pty'a-lin (Gr. imjaXov, saliva). A 

 ferment in saliva, having power 

 to convert starch into sugar. 



Pu'pil (Lat. pupilla). The central, 

 round opening in the iris, through 

 which light passes into the inte- 

 rior of the eye. 



Pus (Lat.). A yellowish -white, 

 creamy liquid produced by sup- 

 puration. It consists mostly of 

 cells floating in a liquid. 



Py-ae'mi-a (Gr. irfov, pus, and af/*a, 

 blood). A form of blood poison- 

 ing produced by the absorption 

 into the blood of morbid matters 

 usually originating in a wound or 

 local inflammation. 



Py-lo'rus (Gr. Trv\wp6s, a gate 

 keeper). The opening of the 

 stomach at the beginning of the 

 small intestine. 



Re'flex (Lat. reflectere, to bend back). 

 Involuntary movements or secre- 

 tion produced by an excitation 

 traveling along a sensory nerve 

 to a center, where it is turned 

 back or reflected along motor or 

 secretory nerves. 



Res'pi-ra'tion (Lat. re-, again, and 

 spirare, to breathe). The act of 

 breathing in and breathing out air. 



Ret'i-na (Lat. rete, a net). The 

 innermost of the three tunics, or 

 coats, of the eyeball, being an 

 expansion of the optic nerve. 



Ri'ma glot'ti-dis (Lat. rima, a chink 

 or cleft). The opening of the 

 glottis. 



Roent'gen rays. See " X-rays." 



Sar'co-lem'ma (Gr. <rdp, flesh, and 

 X^u/ua, a husk). The membrane 

 which surrounds the contractile 

 substance of a striped muscular 

 fiber. 



Scle-rot'ic (Gr. (TK\r]povv, to harden). 

 The tough, fibrous outer coat of 

 the eyeball. 



Se-ba'ceous (Lat. sebum, tallow). 

 Resembling fat ; the name of the 

 oily secretion by which the skin 

 is kept flexible and soft. 



Se-cre'tion (Lat. secernere, to sepa- 

 rate). The process of separating 

 from the blood some essential, 

 important fluid, which fluid is also 

 called a secretion. 



Sem'i-cir'cu-lar ca-nals'. Three 

 canals in the internal ear. 



Sep'ti-cse'mi-a (Gr. o-rj-n-Ti^s, putre- 

 fying, and alfj.a, blood). Blood 

 poisoning; a form of poisoning 

 resulting from the presence in the 

 blood of the products of putre- 

 factive microorganisms. 



Se'ruin (Lat. serum, whey). The 

 clear, watery fluid w T hich separates 

 from the clot of the blood. 





