LABORATORY 



650 



LACCIN 



280 days after conception. L., Abnormal, departing 

 from the normal course. L., Artificial, when effected 

 or aided by other means than the forces of the maternal 

 organism. L., Atonic, labor protracted or rendered in- 

 capable of spontaneous termination by atony of the 

 uterus. L., Conduct of, management, hygienic, medi- 

 cal, or surgical, of the parturient woman. L., Difficult. 

 See Dystocia. L., Dry, when there is a deficiency of 

 the liquor amnii, or when there has been a premature 

 rupture of the bag of waters. L., False, or False 

 Pains. See Pains. L., Induced, labor brought on 

 by artificial means. L», Insanity of. See Insanity. 

 L., Instrumental, one requiring manual or instru- 

 mental means to extract the child. L., Metastatic, 

 labor in which the true pains cease suddenly, and are 

 succeeded by muscular contractions of neighboring 

 organs, bladder, rectum, or of *he muscles of the trunk 

 and limbs. L., Missed, retention of the dead fetus in 

 utero beyond the period of normal gestation. L., 

 Natural, Normal, or Physiologic, when effected 

 by the sole power of the maternal organism. L., 

 Obstructed. See L. Pathologic. L., Pathologic, 

 when deviating from the normal type by reason of weak- 

 ness of the maternal forces, anomalies of the pelvis, or 

 of the fetus, or of complications, all being causes of 

 Obstructed L. L., Postponed, delayed beyond 

 nine months. L., Premature, taking place before the 

 normal period of gestation, but when the fetus is viable. 

 L., Stages of, arbitrary divisions of the period of 

 labor, — the first begins with dilatation of the os, and 

 ends with complete dilatation, so that the head can pass ; 

 the second ends with the expulsion of the child ; the 

 third {placental) consists in the expulsion of the pla- 

 centa. L., Mechanism of, the mechanism by which 

 a fetus and its appendages traverse the birth-canal and 

 are expelled. L. -pains, the pains of, or the contrac- 

 tion of the uterus during, labor. L., Perverse, labor 

 in which there is an abnormal position of the child. 

 L., Precipitate, labor in which the expulsion of the 

 fetus and its appendages takes place with undue celer- 

 ity. L., Protracted, labor prolonged beyond the 

 usual limit (10-20 hours in primiparae, 2-6 hours in 

 multipara). L., Spontaneous, labor accomplished 

 without artificial aid. 



Laboratory {lab'-or-at-o-re) \_laboratorium, from labor- 

 are, to work], A room or place designed for experi- 

 mental work in chemistry, physiology, biology, etc. 



Laborde's Method. See Treatment, Methods of . L.'s 

 Sign. See Death. 



Labrador Tea {lab'-ra-dor). The leaves of Ledum 

 latifolium, demulcent, expectorant, and tonic. Dose 

 of the fid. ext., sjj-ij. Unof. 



Labrose {la'-bros, or la-bros') \labrosus, lipped]. 

 Supplied with lips. Large-lipped. 



Labrum {la' -brum) [L., a lip-edge, margin: //. , 

 Labra~\. In biology, a lip-like structure, usually the 

 upper, when two are present, the lower being the 

 labium. 



Laburnin {lab-er' -nin) \laburnum, laburnum]. Also 

 called Cytisin. An alkaloid found in Cytisus labur- 

 num. 



Laburnum {lab-er' -num) [L.]. The leaves of Cytisus 

 laburnum, the properties of which are due to an alka- 

 loid, cytisin. In small doses it is diuretic and resolvent; 

 in larger doses poisonous, irritating the alimentary tract, 

 and inducing purging, vomiting, and exhaustion. Unof. 



Labyrinth {lab' -ir-inth) [AafibpivBoc, a maze]. A name 

 given to the series of cavities of the internal ear com- 

 prising the vestibule, cochlea, and the semicircular 

 canals. L., Bony. See L. , Osseous. L., Cortical, 

 the intricately arranged collection of uriniferous tubules 

 and blood-vessels filling the intervals in the cortical 



substance of the kidney. See Kidney. L., Mem- 

 branous, the membranqus cavity within the osseous 

 labyrinth, from which it is partly separated by the 

 perilymph. It comprises' two sacs contained within 

 the vestibule, the semicircular canals and the canal of 



Labyrinth of the Ear Laid Open. 

 a. Fovea elliptica. b. Fovea hemispherica. c. Common en- 

 trance of the posterior and superior semicircular canals. 

 d. Opening of the aqueduct of the vestibule, e. Superior 

 semicircular canal, f. Posterior, g. Inferior semicircular 

 canal, h. Spiral canal of cochlea, i. Opening of the aque- 

 duct of the cochlea, j. Lamina spiralis. 



the cochlea. L. of the Kidney. See Labyrinth, Cor- 

 tical. L., Osseous, the bony capsule of the internal 

 ear, communicating in front with the cochlea and be- 

 hind with the semicircular canals. L. Pit. See Ear. 



Labyrinthal {lab-ir-in' -thai) , Labyrinthic {lab-ir-in' ■ 

 thik). See Labyrinthine. 



Labyrinthine {lab-ir-in' -thin) [lajivpivdoc, a maze]. 

 Pertaining to a labyrinth. L. Vertigo. See Meniere' 's 

 Disease. 



Labyrinthus {lab-ir-in' -thus) [L. : pl.,Labyrinthi~\. A 

 labyrinth. 



Lac {lak) [Pers. , lak, lac]. A resinous incrustation 

 produced on the bark of the twigs and branches of 

 various tropical trees {Urostigma religiosa, Mimosa 

 cinerea, Butea frondosa, Schleickera irijuga, of 

 Ceylon, India, and Burmah, Croton lacciferum, of 

 Ceylon, Croton draco, Acacia greggii, Larrea men- 

 cana, of Mexico), by the puncture of the female lac- 

 insect Carteria {Coccus) lacca. This crude exudation 

 constitutes the stick-lac of commerce. Shellac is pre- 

 pared by spreading the resin into thin plates after 

 being melted and strained. In the preparation of the 

 shellac, the resin is freed from the coloring-matter, 

 which is formed into cakes, and is known as I 

 dye. See Pigments, Conspectus of. Button lac differs 

 from shellac only in form, appearing in cakes about 

 three inches in diameter and one-sixth of an inch thick. 

 Bleached lac is prepared by dissolving lac in a 

 boiling lye of pearlash or potassic hydrate, filter- 

 ing and passing chlorin through the solution until 

 all the lac is precipitated. Seed-lac is the residu 

 tained after dissolving out most of the coloring-matter 

 contained in the resin. The common shellac is 

 in varnishes, lacquers, and sealing-wax ; the bleached 

 lac in pale varnishes and light-colored sealing-wax. 

 L.-beet, a fruit used in Siam for diarrhea | 

 dyspepsia. L., Stick, lac as taken from tin 

 on which it is formed. L. sulphuris, milk of sul- 

 phur ; sulphur pnecipitatum (U. S. P.) L., White. 

 See Bleached lac. 



Lacca {lak' -ah). See Lac. 



Laccate {lak' -at) [Pers., lak, lac, or sealing-wax]. 

 In biology, appearing as if varnished or lacquered. 



Laccin {lak'-in) [Pers., lak, lac]. A substance reseo 

 bling wax, extracted from lac. It is insoluble in water, 

 soluble in alcohol, in ether, in hydrochloric acid, and 

 in potassic hydrate. 



