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ears, etc. ; the anterior end of most 

 invertebrate animals containing 

 the cerebral ganglia ; the antlers of 

 deer (zool.) ; the top of a plant when 

 it consists of a mass of leaves ; a 

 compact inflorescence (bot.). 



head case, the outer hard covering 

 of an insect's head (zool.). 



head cell, one of the cells found on 

 the manubrium of the antheridium 

 of Chara (bot.). 



head kidney, the pronephric portion 

 of the kidney, in vertebrates usually 

 represented only in the embryo ; a 

 nephridium usually developed in 

 the cephalic segment of inverte- 

 brates (zool.). 



heart (hart) n. [A.S. heorte."] A hollow 

 muscular organ with a varying 

 number of chambers which by 

 rhythmic contraction keeps up the 

 circulation of the blood (zool.,anat.) ; 

 the core or central portion of a tree 

 or fruit (bot.). 



heat (het) n. [A.S. haetu.] A kind 

 of energy manifested in various 

 ways ; the sensation of warmth 

 produced by stimulation of special 

 organs ; the period of sexual desire 

 (Phys.). 



heat spot, any of the special areas 

 on the skin at which nerve endings 

 sensitive to heat are found (phys.). 



hectocotylus (heVtokot'llus) //. [Gk. 

 hekaton, hundred ; kotyle, vessel.] 

 One of the arms of a male ceph- 

 alopod specialized to effect transfer- 

 ence of sperms to eggs (zool.). 



hedonic (hedon'ik) glands, skin 

 glands found in certain reptiles 

 which secrete muskand are specially 

 active at the rutting season. 



heel(hel). [A.S. Ae/a.] The hinder 

 part of the foot ; the posterior 

 tarsal portion of the foot ; the talon 

 or talonid of a tooth (zool.). 



hekistotherm (hekTs'tothgrm) n. [Gk. 

 hekistos, least ; therme, heat.] A 

 plant that thrives with the minimum 

 of heat, as alpine plants (bot.). 



helicine (heTisin) a. [Gk. helix, 

 spiral.] Spiral ; convoluted ; 

 hoisted ; appl. certain convoluted 

 and dilated arteries in the penis ; 



4 pert, outer rim of the pinna (anat.). 



helicoid (heTikoid) a. [Gk. helix, 

 spiral; eidos, like.] Spiral; shaped 



like a snail's shell ; pert, genus 

 Helix (zool.) ; pert, type of sym- 

 podial branching in which the sym- 

 podium consists of the fork branches 

 of the same side (bot.). 



helicoid cyme, an inflorescence pro- 

 duced by the suppression of the 

 successive axes on the same side, 

 thus causing the sympodium to be 

 spirally twisted (bot.). 



helicotrema (hel'ikotre'ma) n. [Gk. 

 helix, spiral ; trema, hole.] A 

 small opening near the summit 

 of the cochlea by which the two 

 scalae communicate with one 

 another (anat.). 



heliosis (helio'sTs) n. [Gk, Julias, 

 sun.] The production of dis- 

 coloured spots or markings on 

 leaves through the concentration 

 of the sun on them (bot.). 



heliotaxis (he'liotak'sis) n. [Gk. 

 helios, sun ; taxis, arrangement.] 

 Response to the stimulus of the 

 sun's rays. 



heliotropism (he'liot'ropizm) n. [Gk. 

 helios, sun ; trepein, to turn.] The 

 tendency of growing organisms 

 or parts thereof to respond to 

 the stimulus of sunlight (biol.). 



helix (he'llks) n. [Gk. helix, spiral.] 

 The outer rim of the ear (anat.) ; 

 the coiled spiral arrangement of 

 certain structures in the inverte- 

 brates (zool.). 



helmet (heTme't) n. [O.F. helmet, 

 head covering.] The process of 

 the bill of hornbills ; the bony 

 plates covering the head of certain 

 extinct Fishes ; the galea of Insects 

 (zool.). 



helminthology (hel'minthol'dji) n. 

 [Gk. helmins, worm ; logos, dis- 

 course.] The study of the natural 

 history, anatomy, etc., of Worms, 

 especially parasitic forms (zool.). 



helotism (hel'otizm) . [Gk. Helos, 

 Laconian town.] Symbiosis in 

 which the one organism enslaves 

 the other and forces it to labour 

 in its behalf, e.g. in Lichens, in 

 some species of ants (biol.). 



hemelytron (hemeTitron) n. [Gk. 

 hemi, half; elytron, wing.] The 

 thickened forewing of certain 

 Insects ; the elytra of certain 

 Worms (zool.). 



