354 



RESPIRATION. 



them by subjecting them to a sufficiently low pressure. The change of color 

 which ensues when this loosely combined oxygen is removed, is character- 



FIG. 97. 



The Spectra of Oxy-htemoglobin in Different Grades of Concentration, of (reduced) Haemo- 

 globin, and of Carbonic-oxide-haemoglobin. (After Preyer and Gamgee) : 1 to 4, solution of oxy- 

 haemoglobin containing (1) less than 0.01 per cent., (2) 0.09 per cent,, (3) 0.37 per cent., (4) 0.8 per 

 cent. 5, solution of (reduced) haemoglobin containing about 0.2 per cent. 6, solution of carbonic- 

 oxide-hEemoglobin. In each of the six cases the layer brought before the spectroscope was 1 cm. 

 in thickness. The letters (A, a, etc.) indicate Frauenhofer's lines, and the figures wave-lengths 

 expressed in 100,000th s of a millimetre. 



