151 



LESSON XIX 

 HEMOGLOBIN AND ITS DERIVATIVES 



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

 expeiriments as in those described in Lesson IX. 



1. Place some in a haematoscope (see fig. 33, p. 93) in front of the large 

 spectroscope. Note the position of the two characteristic bands of oxyhaemo- 

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

 by the addition of Stokes's reagent (see footnote, p. 92) or ammonium sulphide. 

 By means of a small rectangular prism a comparison spectrum showing 

 the bright sodium line (in the position of the dark hne 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 pm-pose a cell containing a small quantity of oxyhsemoglobin 

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

 carbonic oxide hsemoglobin in front of the sUt in the side of the instrument. 

 Notice that the two bands of carbonic oxide hsemoglobin are very Kke those 

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



Carbonic oxide hsemoglobin 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 hsemoglobin appears. 



4. Acid Haematin. — Add a few drops of glacial acetic acid to dilute blood ; 

 ^e colour changes to brown. Examine with the spectroscope. Compare 

 the position of the absorption band in the red with that of methaemoglobin ; 

 that of acid hsematin is further from the D line (fig. 57, spectrum 7). 



Take some imdHuted blood and add glacial acetic acid as before. Extract 

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

 should then be poured off and examined. The band in the red is seen, and 

 on farther diluting with ether three additional bands appear. 



5. Alkaline Hsematin. — Add to diluted blood a small quantity of strong 

 caustic potash and warm. The colour changes to brown, and with the spectro- 

 scope a faint shading on the left side of the D line is seen (fig. 57, spectrum 8). 



6. Hsemochromogen. — Add ammonium svdphide to a solution of alkaline 



