\ 



4 



LABORATORY MANUAL OF PHYSIOLOGY. 



are also known as Teichman's crystals, after their discoverer (see 

 Fig. 26). 



With dried blood as found in old blood stains, a small crystal of 

 NaCl is added to the acetic acid before boiling. 



This is a good test for the detection of blood stains, but does not 

 identify the source of the blood. 



4. Haematoporphyrin. This is derived from the pigment 

 portion of the haemoglobin, haematin, by a splitting off of the iron 

 radical. 



Mix some dried blood in a test tube with concentrated sulphuric 

 acid. Filter the resulting solution through asbestos. Divide the 



filtrate into three portions. To 

 the first add an excess of dis- 

 tilled water. To the second 

 add a weak solution of NaOH 

 until the solution is slightly 

 alkaline in reaction. To the 



NU ^ ^i^^ third add an excess of acidu- 



^ ^^ lated alcohol. 



^^ The water in the first solu- 



FIG. 26. Haemin Crystals. (Frey.) . M1 . . , , 



tion will precipitate the haema- 



toporphyrin as a brown flocculent mass. The iron of the haematin 

 unites with the acid to form a ferrous salt. 



In the second tube the pigment goes into solution. In the third 

 tube a solution is also formed. The alkaline solution is of a fine 

 red tint changing to a violet in the presence of an excess of the re- 

 agent. The alcoholic solution has a purple color, changing to a 

 bluish violet when strongly acidulated. These solutions, accord- 

 ing to Schaefer, exhibit a magnificent red fluorescence, even when 

 exceedingly dilute. This pigment occurs, in small amounts, in the 

 normal urine, and in larger quantities in certain pathologic condi- 

 tions, such as chronic sulphonal poisoning. It is also closely re- 

 lated to bilirubin, a bile pigment, and haematoidin (Virchow), 

 which is found in old blood clots within the body. 



[74] 



