496 THE BLOOD. 



hsematin. If pure hemoglobin, or the blood-corpuscles, 

 or even the blood itself, be heated with an excess of 

 concentrated acetic acid, with an addition of sodium 

 chloride or other chlorine compounds, hcemin is formed. 

 This crystallizes in microscopical, well-developed, 

 rhombic plates, insoluble in water, alcohol, and ether, 

 of a yellowish-red color ; it yields hsematin and metal- 

 lic chlorides when heated with alkalL s, and is hence, 

 probably, a compound of hsematin with hydrochloric 

 acid.- The formation of these crystals of hsemin is 

 principally made use of for the detection of blood. 



A coloring matter differing from those described is 

 hcemato'idin, which occurs as a decomposition product 

 of a constituent of blood, probably haemoglobin, par- 

 ticularly blood which has been in a stagnated condi- 

 tion for some time outside of the vessels, in extravasa- 

 tions of blood from ruptured Graafian vesicles, in ex- 

 travasations in the brain, in suppurating cavities, etc. 

 It can be prepared most readily from the yellow bodies 

 of the ovaries of the cow. These are triturated with 

 glass-powder ; allowed to stand in contact with chloro- 

 form for several days ; the filtered, yellow solution 

 evaporated at the ordinary temperature; and the resi- 

 due treated with a little ether for the purpose of re- 

 moving fat. It crystallizes in small, transparent 

 prisms of the color of chromic acid, is insoluble in 

 water and alcohol, difficultly soluble in ether, easily 

 soluble in chloroform, forming a yellow solution, and 

 easily soluble in carbon bisulphide, forming a red solu- 

 tion. In many respects, it resembles bilirubin (p. 482), 

 and has frequently been mistaken for this ; it differs 

 from it, however, very materially in its insolubility in 

 alkalies. The yellow coloring matter of the yolk of 

 eggs is probably identical with hsematoidin. 



As, during the circulation of the blood in the body, 

 in its passage through the capillary vessels and the 

 organs of secretion and excretion, transformations of 

 its principal ingredients are incessantly taking place ; 



