HiEMATOPINUS. 



[ 304 ] 



HAIR. 



and kept at a temperature of 80° to 100° F., 

 the crystals may also be obtained. This re- 

 action might be of use in judicial investiga- 

 tions. The addition of water, and a little 

 alcohol or aether to the blood, sometimes 

 favours the separation of the crystals. 



Crystals of hsematoidine have been found 

 within the blood-globules prior to the addi- 

 tion of reagents. 



Their preservation is difficult; it is best 

 effected by washing them wdth alcohol, or 

 this liquid somewhat diluted with water, and 

 di'ying them under the air-pump, or over 

 sulphuric acid. 



BiBL. Virchow, Ann. d. Chem. u. Pharm. 

 1851, June (Chem. Gaz, 1852); Funke, 

 Zeitsch. f. rat. Med. 1851. i. p. 172, 1852. 

 ii. pp. 199 & 288; Kunde, ibid. 1852. ii. p. 

 271 ; Lehmann, Journ.f. prakt. Chemie, Iv. 

 p. 65 {Chem. Gaz. 1852, x. p. 273) ; Ber. 

 d. Gesellsch. d. Wiss. z. Leipzig, 1852. p, 78 

 {Chem. Gaz. 1853. xi. p. ^42), and Physiol. 

 Chemie; Sanderson, Edinb. Monthly Journ. 

 xiii, pp. 216. 521 ; Kolliker, Mikrosk. Anat.; 

 Teichmann, Zeitsch. f. rat. Med. 1853. iii. 

 p. 375. 



H^MATOPINUS, Leach.— A genus of 

 Insects, of the order Anoplura, and family 

 Pediculidse. 



Char. Legs all formed for climbing ; tho- 

 rax generally narrower than the abdomen, 

 and distinctly separated from it; abdomen 

 composed of eight or nine segments. 



This genus contains several species, which 

 live as parasites upon various animals, — the 

 field-mouse, rat, dog, ox, horse, ass, calf, 

 hog, rabbit, hare, squirrel, &c. 



H. suis (PI. 28. fig. 4; fig. 4*, anterior leg). 

 Dusky ferruginous ; abdomen grey or ashy- 

 yellow, flat and membranaceous, with a black 

 horny excrescence surrounding each of the 

 white spiracles ; legs long and thick ; femur 

 transversely striped ; tibia very abruptly cla- 

 vate, dark-coloured at the end ; tarsi with a 

 large fleshy pulvillus. 



Found upon pigs out of condition ; length 

 1-10 to 1-6". 



BiBL. Denny, Monogr. Anopl. Brit. p. 

 24; Gervais, Walckenaer^s Apteres, iii. 301. 

 H^MOCHARIS,Sav.(Pi5dcoZa,Blainv.). 

 A genus of Annulata. 



H. piscium {Piscicola geometra) is a 

 leech-like animal, found upon the carp, 

 tench, roach, &c. Length 1 to 2". 



BiBL. Leo, Mailer's Archiv, 1835; Ley- 

 dig, Siebold and Kolliker'' s Zeitschr. i. ; 

 Brightwell, Ann. Nat. Hist. 1842. ix. II. 

 H^MOPIS, Sav.— A genus of Annulata. 



H. sanguisorba, the common horse-leech. 

 In this animal the teeth are less numerous 

 and more obtuse than in the medicinal leech 

 {Hirudo officinalis). 



HAIL. — The microscopic structure of 

 hail-stones does not appear to be uniform. 

 In some a central nucleus surrounded by 

 concentric layers has been noticed; in others 

 the nucleus is enveloped by a radiating cry- 

 stalline crust ; or again, the entire mass has 

 been found to consist of little spheres of ice. 

 When hail-stones liquefy, a copious evolution 

 of gas takes place. Hail-stones may best be 

 collected for examination in a blanket, which 

 being a bad conductor of heat, retains them 

 longest in the solid state. Connected with 

 the structure and formation of hail-stones, is 

 the composition of spherules of condensed 

 vapour. These are generally believed to 

 consist of films of water enclosing portions 

 of ah', but Dr. Waller's observations have led 

 him to the conclusion that they are simply 

 composed of w^ater. If the former view were 

 correct, those hail-stones which consist of 

 aggregations of icy spherules, should contain 

 air within them, which does not appear to be 

 the case; but in deciding this question, 

 attention must be paid to the principles laid 

 down in the Introduction, p. xxxii, /., 

 which will afi'ord a simple means of deciding 

 the point. 



In some liquefied hail-stones, the spores 

 of fungi and alga3, with infusoria, have been 

 found. 



BiBL. Pouillet, Elemens de Physique, ii.; 

 Waller, Phil. Trans. 1847. p. 23 ; id. Phil. 

 Mag. 1846. xxix. p. 103 and 1847. xxx. p. 

 159 ; Harting. Skizzen aus d. Natur. 



HAIR, OF Animals. — The structure of 

 the hair of animals is very complicated, and 

 requires careful manipulation for its investi- 

 gation. We shall commence with the hair 

 of man, in which it has been the most per- 

 fectly examined. 



Human hair. When a hair is viewed 

 under a low power, it appears black at the 

 sides and light in the middle, so as to convey 

 a notion of its being a tube ; such is not, 

 however, the case, although this notion was 

 long admitted. 



The hairs are secreted by the skin, and 

 consist of modified epidermic formations. 

 Each is implanted in a cutaneous depression, 

 termed the hair-follicle (fig. 296), at the 

 bottom of which it is fixed by a dilatation 

 called the knob or bulb of the hair (c). The 

 free portion, or that projecting beyond the 

 skin, is the shaft or scape (a); and that above 



