POINTED 



1134 



POLARIZATION 



derness is of diagnostic significance, and generally 

 persists in the intervals between attacks. In trigeminal 

 neuralgia these points are at the supra-orbital notch, 

 at the infraorbital, and at the mental foramen. P. 

 of Vision, the position from which anything is ob- 

 served. P., Vital, a spot in the oblongata corre- 

 sponding to the seat of the respiratory center, and 

 puncture of which causes immediate death. 



Pointed [point'-ed) [ME., point, a point]. Having a 

 point. P. Condyloma. See Venereal Wart. 



Pointillage ( pwan' '• til '- yahzli) [Fr.]. Massage by 

 means of the finger-tips. 



Pointing {point'-ing) [ME., point, a point]. The 

 coming to a point. P. of an Abscess, the process 

 by which pus from the deeper structures reaches the 

 surface. 



Poiseuille's Space. The peripheral zone in the capil- 

 lary vessel between the wall of the capillary and the 

 central current of the red blood-discs. 



Poison (poi'-zn) [ME., poisoun, poison]. A substance 

 that destroys the life of an organism or impairs the 

 functions of one or more of its organs. "A substance 

 capable of producing noxious and even fatal effects 

 upon the system, no matter by what avenue it be 

 introduced ; and this, as an ordinary result, in a 

 healthy state of the body, and not by a mechanical 

 action." (Reese.) See Poisons, Table of, pp. 1136- 

 1149. P., Aerial. Same as Miasm. P., Arrow, a 

 poison, generally a vegetable extract, applied by sav- 

 ages to the heads of their arrows. Curare, employed 

 by the inhabitants of Guiana, is one of the best known 

 of these poisons. P. -ash. See Chionanthus. P. -bag. 

 See P. -sac. P., Blood, a substance having a destruc- 

 tive action upon the blood. P., Frog, an animal 

 poison applied by the Indians of Colombia to their 

 arrow-heads. P., Gaboon. See P. of Pahonias. P.- 

 gland, a gland secreting poison. P., Hematic. 

 Synonym of P., Blood. P., Irritant, one producing 

 irritation or destruction, such as mineral acids, alkalies, 

 caustics, and other corrosive substances. P. -ivy, a 

 shrub vine of North America, Rhus toxicodendron. It 

 produces a severe cutaneous inflammation. See Rhus. 

 P., Morbid, the etiologic poisonous element of a 

 specific disease. P., Muscle: 1. A substance that 

 impairs or destroys the proper functions of muscles. 

 2. A poisonous albumin developed during muscular 

 activity. P., Narcotic, one affecting the cerebral or 

 cerebral and spinal centers, producing stupor, delirium, 

 etc., such as opium, hydrocyanic acid, and carbon 

 monoxid. See, also, Antidote, and Drug. P., 

 Nerve, one impairing or destroying the conducting- 

 power of nerves. P. -oak, a low form of the poison- 

 ivy. P., Ordeal, any one of the vegetable poisons, such 

 as Physostigma, used by savages in the trial of accused 

 persons to determine their guilt or innocence. P.- 

 organ, an organic apparatus for producing a poisonous 

 material. P. of Pahonias, or Phonias, a very 

 virulent poison obtained from the seeds of Strophanthus 

 hispidus, and used as an arrow-poison. It is also 

 called Gaboon poison. P., Protoplasmic, one de- 

 stroying the vital properties of living protoplasm. 

 P. -sac, a sac containing or secreting poison ; a 

 poison-gland. P. -vine. See P. -ivy. 



Poisoning (poi'-zn-ing) [ME., poisoun, a poison]. The 

 act of administering or ingesting any poisonous sub- 

 stance in doses sufficient to destroy life or health. P., 

 Blood, a condition in which the quality of the blood 

 is altered by reason of the presence in it of a poison ; 

 ordinarily, synonymous with Septicemia. 



Poisonous {poi' -zn-us~) [ME. ,poisoun, poison]. Hav- 

 ing the properties of a poison ; venomous. 



Poke-root (poh'-rul). See Phytolacca. 



Polar (po / -lar) [polus, a pole]. Pertaining or belong- 

 ing to the poles. P. Crown, the disc of chromatin- 

 grains at each pole of the nuclear spindle inkaryokine- 

 sis. P. Field, the clear space enclosed by the 

 chromatin -loops of the loose skein, in karyokinesis, 

 and in which the nuclear spindle appears. Cf. Sphere 

 of Attraction, Centrosome. P. Globules, two masses 

 of nuclear substance detached from the nuclear 

 spindles during karyokinesis. They appear to be 

 necessary to the complete maturation of the ovum, 

 although they ultimately disappear. Only one polar 

 globule occurs in parthenogenetic ova. They have 

 been described by Fleming in white blood-corpuscles. 

 The significance of the polar bodies is not definitely 

 known. According to certain embryologists the ovum 

 is originally hermaphroditic, the polar bodies repre- 

 senting the male element, which the ovum expels in 

 order to prepare for the entrance of the male pronu- 

 cleus. An analogous condition, leading also to the 

 loss of certain elements, is thought to exist in the 

 spermatozoon, which likewise is originally hermaphro- 

 ditic. Weismann looks upon the polar bodies as 

 masses of ovogenetic nucleoplasm which are expelled 

 from the ovum, in order that the more important 

 germ-plasm may develop actively. The bodies are 

 also known as the polar globules of Robin. P. 

 Method, a method of applying electricity in electro- 

 therapeutics, in which the pole whose distinctive effect 

 is wanted is placed over the part to be treated, and the 

 other pole over some indifferent part. P. Nucleus, 

 in biology, the fourth nucleus in each group at the two 

 extremities of the embryo-sac. P. Reaction, in 

 electricity, the measure of muscular contraction that 

 follows the application of the positive (anode) or 

 negative (kathode) pole to a nerve or muscle. P. 

 Vesicle. Same as P. Globule. P. Zone. See 

 Zone. 



Polarimeter [po-lar-im'-et-er) \_polus, pole ; /uirpov, a 

 measure]. An instrument for determining the degree 

 to which an optically active substance changes the 

 plane of polarization to the right or to the left. 



Polarimetry (po-larim'-et-re) [ polus, pole ; fierpov, 

 measure]. The use of the polarimeter. 



Polariscope {po-lar'-is-kop) [polus, pole; anone'tv, to 

 view]. An optic instrument for exhibiting the polari- 

 zation of light, or for examining substances in polarized 

 light. The essential parts are the polarizing and ana- 

 lyzing prisms. 



Polariscopic (po-lar-is-hop'-ih) [polus, pole ; CKOTreiv, 

 to view]. Pertaining to a polariscope. 



Polariscopy (po-lar'-is-hop-e) [polus, pole; OKOireiv, to 

 view]. The use of the polariscope. 



Polaristrobometer (po - lar - is -tro -bom'- et - er) [ polus, 

 pole; arndftog, a whirling round; fierpov, measure]. 

 A form of polarimeter or saccharimeter that furnishes a 

 delicate means of fixing the plane of polarization as 

 rotated by the sugar- solution under examination. 



Polarite {po'-lar-tt) [polus, a pole]. A filtering- 

 material containing 50 per cent, of magnetic oxid and 

 iron carbonate ; it is used in the artificial filtration <>l 

 sewage. 



Polarity (po-lar'-it-e) [polus, pole]. The state or 

 quality of having poles or points of intensity with 

 mutually opposite qualities. In electro-therapeuticSi 

 that condition of a nerve in which the part nearest the 

 negative pole is in a state of increased, ami that near- 

 est the positive is in a state of decreased irritability. 



Polarization {po-Iar-iz-a'-shun) [polus, pole]. 



act of forming poles or points of intensity having 

 qualities mutually opposite. P., Chromatic, polar- 

 ization accompanied by a play of colors. P., Circu- 

 lar, the turning of the plane of polarization to the 



