PORCUPINE 



1159 



POROTIC 



impure silicate of aluminum, non -transparent and ex- 

 ceedingly infusible. It is made from porcelain-clay, or 

 kaolin ( H„Al.,Si,0 8 -f- H 2 0), derived from feldspar rock 

 bv the atmospheric process known as " weathering." 

 Heated in a furnace, it loses water, and a porous mass 

 is produced. In making porcelain the powdered 

 kaolin is mixed with water to a thick paste, and then 

 molded into the desired shape. A little feldspar, 

 chalk, or gypsum is added to the clay in order to form 

 a fusible silicate, in quantity just sufficient to bind the 

 particles of clay rirmly together. Upon firing, as the 

 process is called, a porous " biscuit-ware " is obtained, 

 which is afterward subjected to the process of glazing. 

 For the finest porcelain the glazing material is feld- 

 spar ; for the cheaper varieties a mixture of clay, 

 chalk, ground-flints, and borax is used. Earthenware 

 is salt-glazed. There are also other methods of glaz- 

 ing. The colors used in decorating porcelain consist 

 of various metallic oxids, and may be applied before 

 or after glazing. P.-glass, a glass which resembles 

 porcelain, made by fusing cryolite, a double fluorid 

 of aluminum and sodium, with sand. P. Teeth, 

 mineral teeth ; incorruptible teeth ; silicious terro- 



lic teeth ; vilrescent teeth ; dental substitutes, 

 resembling, more or less closely, the shape and color 

 of the natural teeth, so constructed that they may be 

 securely fixed to the various attachments employed for 

 their adjustment and retention in the mouth. They 

 ■ire composed of feldspar, silex, and other mineral 

 substances. 



orcupine ( por'-ku-piti) [porcus, ahog ; spina, spine]. 

 A rodent quadruped of the family Hystricidie. It is 

 covered with sharp spines. P. Disease. See 

 Hystrix. P. -men, persons affected with Ichthyosis 

 hystrix. P. -skin, an extreme degree of Ichthyosis 

 hystrix. 



ore | por) [-opoc, a pore]. In biology, a minute cir- 

 cular opening or perforation. P., Abdominal, in 

 certain fishes, the opening by which the abdominal 

 cavity communicates with the exterior, and through 

 which the ova are discharged. Ps. of the Skin, the 

 openings of the ducts of the sebaceous and sweat- 

 glands of the skin. Ps., Sweat, the orifices of the 

 ducts of the sweat-glands. P., Vascular, in the 

 round-worms, a transverse opening situated on the 

 ventral surface and forming the common orifice of 

 the two lateral vessels which are thought to be excre- 

 tory organs, 

 orencephalia i por-en-sef-a'-le-ah) [ -6poc, cavity; 



ji'/oc, brain]. The presence of depressions on 

 the surface of the hemispheres of the brain, owing to 

 absence of portions of brain-substance. The defects 

 are covered by pia and arachnoid, except in cases in 

 which a communication with the ventricles exists. 

 The term is generally restricted to limited congenital 

 defects, although by some it is extended to include 

 those that are acquired. 



orencephalic ( por-en-sefal' -ik) . Same as Poren- 

 \ cephalous. 

 orencephalous (por-en-sef'-al-us} [ -opoc, cavity ; 



brain]. Affected with porencephalia, 

 orencephalus (por-en-sef'-al-us). See Porencephalia. 

 orencephaly ( por-en-sef'-al-e). Synonym of Poren- 

 cephalia. 



oreutes (po-ru'-tez) [-opevetv, to convey]. Ameboid 

 cells of Kollmann, derived from aeroblasts, from which 

 the blood and its corpuscles, the endothelium of the 

 vessels, and the wandering cells are developed, 

 anferous ( por-if'-er-us) [-opoc, pore ; ferre, to bear]. 

 In biology, provided with pores. 



triform (por'-iform) [xopoc, pore; forma, form]. 

 Having the form of a pore. 



Poristotropia ( por-is-to-tro> '-pe-ah) [xopi r eiv, to pro- 

 vide ; Tpo-zi], a turning]. A chemic process by which, 

 according to Ritgen, the existing atoms are destroyed 

 and new atoms produced whenever a new substance 

 is formed. 



Pork [ porcus, hog] . The flesh of swine, Sus scrofa. 

 P., Diseases of, the parasitic diseases are of interest. 

 Pork may be infested with the scolices of the Taenia 

 solium and with the Trichina spiralis. The former, 

 known as cysticercus cellulose, or " measle," is con- 

 tained within a fibrous capsule. If such measly pork 

 is ingested in the raw state by man, the cyst-wall is 

 dissolved in the stomach, and the scolex is set free, and 

 develops into a tape- worm. Pork containing trichinae, 

 if eaten without proper cooking, gives rise to trichi- 

 niasis, a grave and sometimes fatal disease. See 

 Trichiniasis and Measles; also Cysticercus and Tri- 

 china, under Parasites [Animal), Table of. An im- 

 portant infectious disease of swine is Rouget du pore, 

 Schweinerothlauf or Swine-plague. See Rouget du 

 pore, and Bacillus erysipilatos suis, Pasteur, and 

 Bacillus of Swine-plague, Marseilles, Rietsch and 

 Jobert, under Bacteria, Synonymatic Table of 



Pornograph (por / -no-graf) [tropin/, prostitute ; ypdfeiv, 

 to write]. An obscene picture or writing. 



Pornographer (por-nog'-ra-fer) [-opvrj, prostitute; 

 ypdptiv, to write]. One who writes of prostitutes or 

 obscene subjects. 



Pornographic (por-no-graf'-ik) [-oprr/, prostitute ; 

 ypaoeiv, to write]. Of or pertaining to pornography. 



Pornography ( por-nog* '-ra'fe ) [-opv?/, a prostitute; 

 -jpaoeiv, to write]. I. A treatise on prostitution, with 

 reference to public hygiene. 2. Obscene writing. 



Porocele (pc/-ro -sel) [tropoc, callus ; Kq/.q, tumor]. A 

 scrotal hernia in which the coverings are calloused or 

 hardened. 



Porodinic (po-ro-din f -ik) [iropoc, a pore ; Sivoc, rota- 

 tion, a round area]. In biology, reproduction by 

 means of genital pores ; distinguished from Schizo- 

 dinic. Cf. A r ephrodinic, Idiodinic. 



Porokeratosis ( po - ro - ker - at- o f - sis) [-opoc, callus ; 

 r.kpac, a horn]. A keratosis appearing in raised or 

 smooth areas, of varying size, irregular form, circum- 

 scribed outline, at the summit of which a thin layer 

 of horny tissue of linear arrangement is present. The 

 affection is usually seated on the dorsal aspect of 

 the hands and feet (never on the palmar or plantar 

 surface), the extensor aspect of the forearms and legs, 

 neck, face and scalp. 



Poroma (po-ro'-mah) [tropofm] . A callosity. 



Poromphalocele (po-rom-fal'-o-sel) [-opoc, callus ; 

 buoa'/.oc, navel ; ktj/.j], tumor]. An umbilical hernia 

 with hardened contents. 



Poromphalon, Poromphalos (po-rom'-fal-on,po-rom'- 

 fal-os). Synonym of Poromphalocele. 



Porophyllous ( por-o-fil' -us)[-6poc, pore ; oi//ov, leaf]. 

 In biology, having leaves sprinkled with transparent 

 points. 



Poroplastic (por-o-plas'-tik) [~6poc, pore; iz/aaoetv, 

 to mold]. Porous and plastic. P. Felt, a porous 

 felt which is readily molded ; it is used in the pre- 

 paration of splints and jackets. P. Jacket, a form of 

 jacket used in the treatment of spinal curvatures. 



Porose (por'-oz) [porus, a pore]. In biology, per- 

 forate. 



Porosis ( po-ro'-sis) [-xopoc, callus]. The formation of 

 callus. P., Osteo-. See Osteoporosis. P. palpe- 

 brae. Synonym of Chalazion. 



Porosity ( por-os' -it-e) [ff opoc, cavity]. The condition 

 of being porous. 



Porotic ( po-rof-ik) [-opoc, callus]. Favoring the 

 formation of callus. Of the nature of callus. 



