DIASTOLIC 



372 



DICROTIC 



during its rhythmic cycle or beat. It is applied also 

 to the dilatation of the arteries by the heart's con- 

 traction. 



Diastolic (di-as-tol f -ik) [diaaroAtj, a drawing apart]. 

 Pertaining to diastole. D. Impulse, the back-stroke. 

 D. Murmur. See Murmur. D. Thrill, the vibra- 

 tion felt in the region of the heart during the diastole 

 of the ventricles. 



Diastrephia (di-as-tref-e-ah) [did, apart ; GTpktyziv, to 

 turn]. Insanity marked by acts of cruelty and by 

 gross perversion of the moral sense. 



Diatactic (di-at-ak 1 '-tik) [diardaasiv, to make ready]. 

 Preparatory. D. Action, the supposed molecular 

 establishment of unions between different brain-cells 

 and nerve-centers preparatory to coordinated motor 

 activity. 



Diatela (di-at-e / -lah) [did, between ; tela, a web]. The 

 membranous roof of the diacele (third ventricle). 



Diaterma (di-at-er' '-mak) [did, between; rtppa, end]. 

 A portion of the floor of the diacele. It has a nearly 

 dorso-ventral direction. 



Diathermal or Diathermanous {di-ath-er'-mal, di- 

 ath-er'-man-us) [did, through ; dip/ur/, heat] . Trans- 

 parent or diaphanous to the waves of radiant heat. 



Diathermancy (di-ath-er' -man-se) [<5<d, through; Okpfit], 

 heat]. Permeability to rays of heat. 



Diathesis (di-ath' -es-is) [did, through ; ndevai, to ar- 

 range]. A state or condition of the body whereby it is 

 especially liable to certain diseases, such as gout, cal- 

 culus, diabetes, etc. It may be acquired or heredi- 

 tary. D., Hemorrhagic. Stt Hemophilia. 



Diathetic (di-ath-ef -ik) [did, through; ndevai, to ar- 

 range]. Relating to a diathesis. 



Diatom (di'-at-om). One of the Diatomacece, a group 

 of microscopic Alga. 



Diatomic (di-at-om' -ik) [dig , two ; aro/zoc, atom]. In 

 chemistry, consisting of two atoms ; specifically applied 

 to hydrates that have two hydrogen atoms united to the 

 nucleus radical by oxygen. 



Diatomin (di-af '-o-min) [did, through ; TEfivsiv, to 

 cut]. The yellowish-brown coloring-matter of diatoms. 

 It is also called Phycoxanthin. 



Diaxon (di-aks' '-on) [die, two ; a£ui>, axis]. In biology, 

 having two axes. 



Diazo- (di-a'-zo-) [die, two ; azotum, nitrogen]. In 

 chemistry, a prefix signifying that a compound contains 

 phenyl, C 6 H 5 , united with a radical consisting of two 

 nitrogen atoms. D.-acid, one of certain volatile 

 liquids of yellow color and peculiar odor, which 

 distil undecomposed with steam or under reduced pres- 

 sure. They are slightly soluble in water, but mix 

 readily with alcohol and with ether. D. -compound, 

 in chemistry a compound containing a group consisting 

 of phenyl (C 6 H 5 ) united with a radical consisting of 

 two nitrogen-atoms (whence the name). D. -reac- 

 tion or test, a urinary test, originally thought to be 

 especially valuable in the diagnosis of enteric fever. It is 

 not found in the urine of healthy persons. The test is 

 made by mixing 200 parts of sulphanilic acid solution 

 (concentrated solution in water) with io parts of pure 

 hydrochloric acid, and 6 parts of nitrite of sodium 

 solution (i : 200). To this mixture add an equal 

 volume of urine with sufficient ammonia to render the 

 whole alkaline. A bright or carmin-red denotes the 

 reaction. See Tests, Table of. 



Diazobenzene (di-a-zo-ben f -zen) [dis, two ; azotum, 

 nitrogen ; benzoin] . The nitrogenous body called Tyro- 

 toxicon, q. v. 



Dib [E. dial]. The knee-pan or ankle-bone of a 

 sheep's leg. 



Dibasic (di-ha' -sik) [dig, twice; fidaig, base]. Having 

 two bases. D. Acids. See Acids. 



Dibenzyl (di-ben' '-zil) [die, twice ; benzoin'], C U H U . 

 A compound prepared by the action of sodium upon 

 benzyl chlorid. It crystallizes in large prisms, melt- 

 ing at 5 2° C. and boiling at 284 C. 



Diblastic [di-blas' -tik) [die, double ; ffKaardg, germ] . 

 Referring to any theory of disease that ascribes it to a 

 double agency. 



Dibothrium idi-both' -re-um) [L. ]. A genus of ces- 

 tode worms. D. latum. See Bothriocephalus latus. 



Dibromindone [di-bro-min' -don) [dig, double ; (ipuuog, 

 a stench], C g H 4 Br 2 0. A compound derived from 

 dibromcinnamic acid. It consists of orange-yellow 

 needles, with an odor resembling that of quinone. It 

 melts at 123 . 



Dicephalism (di-sef '-al-izm) [die, two; nt<j>aArj, head]. 

 The condition of having two heads. 



Dicephalous {di-sef f -al-us) [Sir, two; ite<paAi}, head]. 

 Two-headed. 



Dicephalus (di-sef / -al-us) [dig, two ; K£<paA?j, a head]. 

 A monster having two heads. 



Dicerous (dis / -er-us) [dig, two; nkpag, a horn]. In 

 biology, having two antennae. 



Dichasium (di-ka'-se-um) [di^aacg, division]. In 

 biology, applied to a cyme having two axes. 



Dichastasis (di-kas' '-tas-is) [dixaeig, division]. In 

 biology, spontaneous fission. 



Dichasteres (di-kas-te' -rez) [dixdijeiv, to divide]. An 

 old name for the incisor teeth. 



Dichlamydeous (di-klam-id' -e-ns) [dig, two ; ^/la/zvf, a 

 mantle]. In biology, applied to flowers having both 

 floral envelops. 



Dichogamy (di-kog' '-a- me) [dixa, in two ; yd/uog, mar- 

 riage]. In biology, a provision for cross-fertilization 

 of flowers by the maturation of the reproductive ele- 

 ments of the same flower at different times. 



Dichotomous (di-kof -o-mus) [dixa, in two ; te/iveii', 

 to cut]. In biology, divided, forked or having a 

 dual arrangement. 



Dichroism (di'-kro-izni) [dig, double; xP^a, color]. 

 The phenomenon of difference of color in bodies 

 when viewed by reflected or by transmitted light. 



Dichromatism (di-kro' -mat-izm). Same as Color- 

 blindness. 



Dicinchonin (di-sin' -kon-in) [dig, double ; cinchona'] , 

 C 38 H 44 N 4 O r An alkaloid of Cinchona bark, an 

 amorphous solid, melting at 40 C, readily soluble in 

 alcohol and ether. 



Diclesium (di-kle' -se-tini) [dig, two ; KAsieiv, close]. In 

 biology, an achenium having a persistent calyx or 

 perianth. 



Diclinous (di-kli' -nus) [dig, two ; kHvt], a bed] . In 

 biology, having the stamens and pistils in separate 

 flowers. 



Dicochirurgea (di-ko-ki-rer'-je-ah) [dint], justice; 

 Xeipovpyia, surgery]. Forensic surgery. 



Dicotoin (di-ko / -to-in) [dig, double ; Coto], A deriva- 

 tive of cotoin present in coto bark. 



Dicotyledon (di-kot-il-e'-don) [dig, two ; kotv'/ 

 a cavity]. In biology, a term introduced by J. Kay 

 in 1682, for a plant whose embryo has two seed-leaves 

 or cotyledons. 



Dicranous (di-kra' '-nus) [diapavog, two-headed]. 

 Dicephalous. 



Dicranus (di-kra' -nus) [dig, double; Kpdvov, head]. 

 A dicephalous monster. 



Dicrotic (di-l-ivf -ik)[diKporog, double beating]. Having 

 a double beat. D. Pulse, a term applied to a pulse 

 that imparts the sensation of a double beat at each 

 pulsation. D. Wave, the wave of recoil, or the 

 second smaller ascending wave of the sphygmograi>liie 

 tracing. It is generated by closure of the aortic 

 valves. 



