THE BLOOD 



249 



from the sun, the spectrum will present vertical dark lines, the so-called 

 Fraunhofer's lines. They are given from A to F in Fig. 103. If a colored 



FIG. 100. THE SPECTROSCOPE. A. Telescope. B. Tube for the admission of light and 

 carrying the collimator. C. Tube containing a scale, the image of which when illuminated is 

 reflected above the spectrum. D. The fluid examined. (Landois and Stirling.) 



medium be held in front of the slit so that the light has to pass through if first, 

 certain dark bands will appear in the spectrum, owing to the absorption of 

 certain rays. 



Yellow, 



Green. 



Cyan Blue. 



70 



E b 



Oxy 



hemoglobin 

 0.8 %. 



FIG. 101. SPECTRA OF HEMOGLOBIN AND SOME OF ITS COMPOUNDS. (Landois and Stirling.) 



Dilute solutions of arterial blood show absorption bands between the 

 Fraunhofer lines, D and E, in the green and yellow portion of the spectrum. 

 (See Fig. 101.) The band nearest D, frequently designated as alpha, is dark 



