248 



TEXT-BOOK OF PHYSIOLOGY. 



with the spectroscope, and which are so ^characteristic as to serve for their 

 identification. 



In principle a spectroscope consists of a prism which decomposes the 

 light from a narrow slit into a band of all the spectral colors. A form of 



FIG. 109. 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. (Landosi and Stirling.} 



Yellow. 



Green. 



Cyan Blue. 



Oxy 



hemoglobin 

 0.8 %. 



FIG. 1 10. SPECTRA OF HEMOGLOBIN AND SOME or ITS COMPOUNDS. 

 (Landois and Stirling.') 



spectroscope in common use is that shown in Fig. 109. It consists of a 

 tube, B, which has at one end a slit that can be narrowed or widened by 

 means of a screw. The light, having passed through it, falls on an achro- 

 matic convex lens (called the collimator) at the opposite end of the tube 



