LESSON XIX 



HAEMOGLOBIN AND ITS DERIVATIVES 



Defibrinated ox-blood suitably diluted may be used in the following 

 experiments as in those described in Lesson IX. 



1. Place some in a haematoscope (see fig. 33, p. 116) in front of the large 

 spectroscope. Note the position of the two characteristic bands of oxy haemo- 

 globin ; these are replaced by the single band of haemoglobin after reduction by 

 the addition of Stokes's reagent (see footnote, p. 115) or ammonium sulphide. 

 By means of a small rectangular prism a comparison spectrum showing 

 the bright sodium line (in the position of the dark line named D in the solar 

 spectrum) may be obtained, and focussed with the absorption spectrum. 



2. Obtain similar comparison spectra by the use of the microspectroscope. 

 For this purpose a cell containing -a small quantity of oxyhsemoglobin 

 solution may be placed on the microscope stage, and a test-tube containing 

 carbonic oxide haemoglobin in front of the slit in the side of the instrument. 

 Notice that the two bands of carbonic oxide haemoglobin are very like those 

 of oxyhaemoglobin, but are a little nearer to the violet end of the spectrum. 



Carbonic oxide haemoglobin may be readily prepared by passing a stream 

 of coal gas through the diluted blood. It has a cherry-red colour and is not 

 reduced by the addition of ammonium sulphide (fig. 57, spectrum 4). 



3. Methaemoglobin. Add a few drops of ferricyanide of potassium to 

 dilute blood and warm gently. The colour changes to mahogany-brown. 

 Place the test-tube in front of the small direct-vision spectroscope. Note 



the characteristic band in the red (fig. 57, spectrum 5). On dilution other 

 bands appear (fig. 57, spectrum 6). Treat with ammonium sulphide and 

 the band of haemoglobin appears. 



4. Acid Haematin. (a) Prepare the following mixture : 150 c.c. of'90-per- 

 cent. alcohol and 6 c.c. of concentrated sulphuric acid ; take about 5 c.c. of 

 this mixture and boil it in a test-tube. While still hot drop into it a few 

 drops of undiluted defibrinated blood, and filter. Note the brown colour of 

 the filtrate. Compare the position of the absorption band in the red with 

 that of methaemoglobin ; that of acid haamatin is further from the D line 

 (fig. 57, spectrum 7). 



(6) Add some glacial acetic acid to undiluted defibrinated blood. Extract 

 this with ether by gently agitating it with that fluid. The ethereal extract 

 should then be poured off and examined spectroscopically. The band in the 

 red is seen, and on further diluting with ether three additional bands appear. 



5. Alkaline Haematin. (a) Add to diluted blood a small quantity of strong 



