VISIBLE SPECTRUM OF OXYH^EMOGLOBIN. 



21 I 



The spectrum as seen with solutions of varying concentration. 



When well-arterialised defibriiiated blood (containing on an average 

 from 12 to 14 per cent, of oxyhsemoglobin) is diluted with nine times 

 its volume of distilled water, and a stratum 1 cm. thick is brought before 

 the slit of the spectroscope, it will be found that the whole of the 

 spectrum is absorbed, with the exception of the red end, or rather of 

 those rays having a wave length greater than about 600 millionths of 

 a millimetre (X 600). 



If, now, the blood solution be gradually diluted, a point is reached 

 at which the spectrum is (proceeding from the red end) clear up to D 

 (\ 598), and a strip of green is visible between I and F (x 518'3-X 486'1). 

 Between D and b the absorption is intense (see Plate I., Spectrum 4), 

 and beyond F no trace of light appears. On diluting still further, that 



FIG. 23. The hseinatinometer. 



FIG. 24. The lisematoscope. 



which appeared as a single wide absorption-band between D and b, and 

 afterwards as the solution was progressively diluted between D and E, 

 is seen to resolve itself into two distinct absorption-bands, separated by 

 a green interspace ; the violet end of the spectrum is still powerfully 

 absorbed (Plate I., Spectrum 3). 



Of the two absorption-bands just referred to, the one next to D is 

 narrower than its fellow ; it has more sharply denned borders, and to the 

 eye appears more intense ; its centre corresponds to X 579, and we may 

 conveniently distinguish it as the absorption-band a in the spectrum of 

 oxyheemoglobin. 



The second of these absorption-bands, i.e. the one next to E, which 

 we shall designate the band /3, is broader, has less sharply-defined edges, 

 and its centre corresponds approximately to X 553*8. Between the two 

 bands is a green interspace. 



On diluting the solution more and more largely, and continuing to 

 examine a stratum 1 cm. thick, the absorption of the violet end becomes 



