

POIKILOCYTHEMIA 



Poikilocythemia (poi-kil-o-si-the'-me-ah) \ieouu7jor, 

 varied; kvtot, cell; atua, blood]. The presence of 

 poikilocjtes in the blood. 



Poikilocytosis {poi- kil-o- si-to* '-sis) [—ouu/joc, varied ; 

 ;, cell]. A condition of the blood marked by ir- 

 regularity in the shape of the red corpuscles ; it occurs 

 preeminently in pernicious anemia, but also in other 

 forms of anemia. 



Poiiulothermal (poi- kil- o-ther'- ma/). Synonym of 

 i'athermic. 



Poikilothermic ( poi-kil-o-ther 4 '-mik) [ttouu?jOC, varied ; 

 tiipuij, heat]. Varying in temperature according to 

 the surroundings. A term applied to cold-blooded 

 animals, the temperature of which adapts itself easily 

 to their environment. 



t [ME.,/w'«/, a point]. The sharp end of an ob- 

 in the mathematic sense, that which has position 

 it no dimensions. P., Alveolar, the central point 

 the lower margin of the upper alveolar arch. P. 

 iphysaire, P., Apophyseal, a name given by 

 rousseau to a tender spot over the spinous process of 

 vertebra, which, in neuralgic affections, corresponds 

 the origin of the nerve involved. P., Auricular, 

 craniometry, the center of the external auditory 

 us. P., Boiling, the degree of temperature at 

 hich a liquid passes into the vaporous state with 

 ebullition. P., Cardinal, in optics, one of the six 

 points that determine the direction of the rays enter- 

 ing or emerging from a series of refracting media. 

 P., Cardinal, of Capuron. See Pelvis. P., Cra- 

 niometric. See Craniometric Points. P., Critical 

 (of gases), a temperature at or above which a gas can- 

 not be liquefied by pressure alone. Different gases 

 have different, but fixed critical points. P., Critical 

 (of liquids), that temperature at which a liquid, regard- 

 less of the pressure to which it is subjected, assumes 

 a gaseous form. P., Deaf (of the ear), one of certain 

 points near the ear where, as shown by Urbantschitsch, 

 a vibrating tuning-fork cannot be heard. The fork is 

 held perpendicularly and is moved from the zygoma 

 backward toward the occiput. The first point is at 

 the lower end of the tragus; the second, where the 

 helix intersects the line along which the fork is moved. 

 P., Dew, the temperature at which the atmospheric 

 moisture is deposited as dew. P. of Dispersion, 

 in optics, the virtual focus. Ps. douloureux, the 

 tender spots at the exit of nerves the seat of neu- 

 ralgic pain. See Ps., Valleix's. P. of Election, in 

 surgery, that point at which a certain operation is done 

 by preference. P., Erb's, the supraclavicular point, 

 a point above the middle of the clavicle where a 

 group of muscles consisting of the deltoid, biceps, 

 brachial is amicus and supinator longus can be stimu- 

 lated to contraction. P., Eye: i. An ocellus, q. v. 

 2. The bright circle seen at the crossing-point of the 

 rays above the microscopic ocular. P., Far-, the re- 

 motest point of distinct vision; in the emmetropic eye, 

 it is at infinity, but it is practically considered to be at 

 20 feet from the eye ; in the myopic eye at a finite dis- 

 tance in front of the eye ; in the hyperopic eye, beyond 

 infinity. — practically beyond 20 feet P., Fixation, 

 that point on the visual axis at which an object is most 

 distinctly seen. P., Focal, one of the two principal 

 foci of a dioptric system. In the eye there is an ante- 

 rior and a posterior focal point. The former is that 

 point at which emerging rays that are parallel in the 

 vitreous would converge in front of the eye ; while 

 the posterior is that point in the back of the eye 

 at which entering rays, that are parallel when they 

 strike the cornea, meet. P., Freezing, the degree 

 of temperature at which a liquid substance, usually 

 water or watery fluids, becomes solid. P., Fusing, 





1133 POINT 



P., Fusion. Synonym of P., Melting. P., Hystero- 

 epileptogenous, P., Hysterogenic. See Zone. P. 

 of Incidence, in optics, that point on a surface upon 

 which a ray of light falls. P., Intersuperciliary, the 

 central point of a line joining the most prominent 

 points of the two superciliary arches. P., Jugal, the 

 point of intersection of a line tangent to the upper 

 border of the zygoma and one marking the posterior 

 border of the frontal process of the malar bone. P. 

 of Least Resistance. See Locus minoris residen- 

 tial. P., Malar, the moat prominent point on the 

 external surface of the malar bone. P., McBurney's, 

 a point two and a half inches distant from the anterior 

 superior spine of the right ilium, on a line drawn from 

 the spine to the umbilicus. It is often the seat of 

 greatest tenderness in appendicitis. P., Melting, the 

 degree of temperature at which fusible solids begin to 

 melt. P., Metopic, the glabella, q. v. P., Motor, the 

 point on the surface of the body corresponding to the 

 place where the motor nerve enters a muscle, and where 

 an electrode must be applied to produce the maximum 

 contraction of the muscle by electric stimulation. See 

 Motor Point. P., Nasal. Synonym of Nasion. P., 

 Near-, the nearest point at which the eyes can accom- 

 modate to see distinctly. P., Near-, Absolute, the 

 nearest point at which accommodation in a single eye 

 is still possible without vision becoming indistinct. 

 P., Near-, Binocular, the nearest point at which the 

 means of accommodation and the convergence of the 

 visual axes of an object can be seen distinctly. P., 

 Nodal, in optics, the center of curvature of a spherical 

 lens or refracting surface, through which rays of light 

 pass, joining conjugate points. P., Occipital, the 

 pointed posterior extremity of the occipital lobe of 

 the brain. P., Occipital, Maximum, in craniometry, 

 the point of the longest antero-posterior diameter which 

 is most distant from the glabella. P., Ophryon. Syno- 

 nym of Ophryon. P., Orbital, External, in crani- 

 ometry, the most prominent point at the outer edge of 

 the orbit. It is just above the fronto-malar bones. 

 P. of Ossification, the center of ossification in a bone. 

 P., Painful, the point where a nerve, the seat of neu- 

 ralgia, is tender on pressure. It is usually at the exit 

 of the nerve from a bony canal, or where it passes 

 through fascia. See Ps., Valleix's. P., Physio- 

 logic Middle {of the retina), the fovea centralis. Ps., 

 Principal, in optics, the two points in the optic axis 

 of a lens that are so related that lines drawn from these 

 points to the corresponding points in the object and 

 its image are parallel. P. of Reflection, in optics, 

 the point from which a ray of light is reflected. P. 

 of Refraction, in optics, the point at which a ray of 

 light is refracted. P. of Regard, the point at which 

 the eye is directly looking. Its image falls in the 

 middle of the macula lutea. P., Retinal, Corres- 

 ponding. See P., Retinal, Identical. P., Retinal, 

 Disparate, one of those points on the retinae whence 

 images are projected, not to the same, but to different 

 points in space. Ps., Retinal, Identical, correspond- 

 ing points on the two retinae, the images of which are 

 projected to the same spot in space. P. of Sight. 

 Same as P. of Vision. P. , Subnasal, in craniometry, 

 the middle of the inferior border of the anterior nares, 

 or the root of the anterior nasal spine. P., Supra - 

 auricular, in craniometry, the point at the root of 

 the zygomatic process directly over the auricular point. 

 P., Supraclavicular. See P., Erb's. P., Supra- 

 nasal. Same as Ophryon. P., Supra-orbital, a 

 tender point in neuralgia just above the supra-orbital 

 notch. P., Vaccine. See Vaccine Point. Ps., 

 Valleix's (Pointes douloureux), the points at which 

 neuralgic nerves are tender on pressure. This ten- 



