56 STUDIES IN ADVANCED PHYSIOLOGY. 



Blood Crystals. 



As before stated, haemoglobin can be dissolved out of 

 a corpuscle by adding to the blood an excess of water, 

 chloroform, or other solvent. If to such a solution, made 

 icy cold, some alcohol be added, the haemoglobin will 

 separate, and fall to the bottom as well-defined red crystals 

 called blood or haemoglobin crystals. It is exceedingly 



* . . - 



*' - 



Fig. 9. HEMOGLOBIN CRYSTALS. 

 1, a typical crystal. Fig. 10. HEMIN CRYSTALS. 



difficult to preserve these crystals, as they disintegrate 

 easily. 



Under ordinary circumstances haemoglobin disintegrates ' 

 into an albumen called globulin, and into a dirty brown 

 substance called haematin. Hence the dirty brown red 

 appearance of old stains and the discoloration of the skin 

 which follows a severe bruise and is familiar to every boy 

 as a " black eye." The discoloration of the skin is due to 

 the blood which has stagnated in the bruised tissues, the 

 haemoglobin of which has disintegrated into a substance 

 almost identical with haematin called haematoidin. 



Sometimes it becomes desirable to establish the identity 

 of stains believed to be blood stains. It is not at all un- 

 usual in legal proceedings incident to murder trials, to 

 attempt to prove that certain spots or stains are really 

 blood stains. Such a proof is easily made. If from the 

 old blood stain some of this dark haematin be removed to a 



