

ILEMATOIDIN. 2J 



plates, or rods ; sometimes they are single at other times they are aggregated in 

 groups, often crossing each other. Some kinds of blood (ox and pig) yield very 

 irregular, scarcely crystalline, masses. The crystalline forms of hsemin are identical 

 in all the different kinds of blood that have been examined. They are doubly 

 refractive ; under the polarization microscope they are a glancing yellow, appear- 

 ing raised on the dark held, with a strong absorption of the light parallel to the 

 long axis of the crystals (Folk and Morache). They are pleochromatic : by 

 transmitted light they are mahogany-brown, and by reflected light bluish-black, 

 glancing like steel. 



(1) Preparation from Dry Blood-Stains. Place a few particles of the blood-stain on a glass 

 slide, add 2 to 3 drops of glacial acetic acid and a small crystal of common salt ; cover with a 

 cover-glass, and heat gently over the flame of a spirit lamp until bubbles of gas are given off. 

 On cooling, the crystals appear in the preparation (fig. 19). 



(2) From Stains on Porous Bodies. The stained object (cloth, wood, blotting paper, earth) 

 is extracted with a small quantity of dilute caustic potash, and afterwards with water in a 

 watch-glass. Both solutions are carefully filtered, and tannic acid and glacial acetic acid are 

 added until an acid reaction is obtained. The dark precipitate which is formed is collected on 

 a filter and washed. A small part of it is placed on a microscope slide, a granule of common 

 salt is added, and the whole dried ; the dry stain is treated as in (1) (Struwc). 



(3) From Fluid Blood. Dry the blood slowly at a low temperature, and proceed as in (1). 



(4) From Dilute Solutions of Hsemoglobin. (a) Struive's Method. Add to the fluid, am- 

 monia, tannic acid, and afterwards glacial acetic acid, until it is acid ; a black precipitate of 

 tannate of hsematin is thrown down. This is isolated, washed, dried, and treated as in (1), but 

 instead of NaCl a granule of ammonium chloride is added. 



Hsemin crystals may sometimes be prepared from putrefying or lake- coloured 

 blood, but they are very small, and the test often fails. When mixed with iron- 

 rust, as on iron weapons, the blood-crystals are generally not formed. In such cases, 

 scrape off the stains and boil them with dilute caustic potash. If blood be present, 

 the dissolved haematin forms a .fluid, w T hich in a thin layer is green, in a thick 

 layer red (H. Rose). 



Haemin crystals have been prepared from all classes of vertebrates and from the blood of 

 the earth-worm. From the blood of the ox and pig they may be almost amorphous. 



Chemical Characters. They are insoluble in water, alcohol, ether, chloroform ; but con- 

 centrated H 2 S0 4 dissolves them, expelling the HC1, and giving a violet-red colour. Ammonia 

 also dissolves them, and if the resulting solution be evaporated, heated to 130 C, and treated 

 with boiling water (which extracts the ammonium chloride), hsematoporphyrin identical with 

 Mulder's iron-free hsematoin, and with Preyer's hsematoin, is obtained (Hoppe-Seyler). 

 It is a bluish-black substance, which on being pounded forms a brown and amorphous powder. 

 Its solutions in caustic alkalies are dichroic : in reflected light brownish-red ; in transmitted 

 light, in a thick stratum, red in a thin one, olive-green. The acid solutions are monochro- 

 matic and brown. 



Preparation in Bulk. To obtain it in quantity, heat dried horse's blood with 10 parts of 

 formic acid. If the crystals be suspended in methyl alcohol, on adding iodine and heating 

 them they dissolve with a purple colour; after adding bromine, 

 brown ; and after passing chlorine gas, green ; all these give a 

 characteristic spectrum (Axenfeld). 



The glacial acetic acid may be replaced by oxalic or tartaric 

 acid, the commou salt by salts of iodine or bromine ; in the latter 

 case similar bromine- or iodine-hsematin is formed (Bikfalvi). 



20. HJEMATOIDIN. Virchow discovered this im- 

 portant derivative of haemoglobin. It occurs in the IU^ ^ {) 

 body wherever blood stagnates outside the circulation, ^^ ^ 



and becomes decomposed as when blood is extra vasated w ''. ' , 



into the tissues e.g., the brain in solidified blood- iiamatoidin crystals, 

 plugs or thrombi; especially in veins; invariably in the Graafian follicles. It con- 

 tains no iron (C^HggNjOg), and crystallises in clino-rhombic prisms (fig. 20) of a 

 yellowish-brown colour. It is soluble in warm alkalies and chloroform. Very 

 probably it is identical with the bile-pigment bilirubin. [When acted upon 



