56 OXYGEN-COMBINATIONS OF HEMOGLOBIN. 



gases, particularly carbon monoxid, and heating to the boiling-point. 

 Also in the circulating blood the oxygen is readily given up to the 

 tissues of the body, so that in animals dead from suffocation only 

 gas-free reduced hemoglobin is found in the veins. Also con- 

 stituents of the serum and sugar remove the oxygen. By addition of 

 reducing substances to a solution of oxyhemoglobin, as, for instance, 

 ammonium sulphid, the two bands of oxyhemoglobin disappear and 

 reduced gas-free hemoglobin results (Fig. 15, 4). This is recognizable 

 from its wide ill-defined absorption-band. Agitation with air, how- 

 ever, at once restores both bands through the formation of oxyhemo- 

 globin. Solutions of oxyhemoglobin are readily distinguished by their 

 scarlet color from the wine- violet-red tint of reduced hemoglobin. 



The yellowish-green color of the solar spectrum thrown isolated upon the 

 closed upper eyelid causes a sensation of dark. If the base of two fingers be 

 ligated to the point of interrupting the circulation it will be seen on spectro- 

 scopic examination of the intervening red cutaneous seam that the oxyhemo- 



(X9 



aBC 



Eb F 



FIGS. 13 and 14. The Absorption-spectra of Oxyhemoglobin (Fig. 13) and of Gas-free Hemoglobin (Fig. 14 ) 

 with Increasing Concentration. The letters of the lower line indicate the Fraunhofer lines. The figures 

 at the side indicate the percentage-strength of the solutions (after Rollett). 



globin is soon transformed into reduced hemoglobin. This reaction is delayed 

 under the influence of cold; it is accelerated in youth, during muscular activity 

 or with suppression of breathing and generally also in the presence of fever. A 

 beating heart also exerts a reducing influence upon oxyhemoglobin. The absorp- 

 tion-spectra naturally vary with the concentration of the solution ; in the presence 

 of a greater amount of hemoglobin the bands are wider and may become confluent, 

 and finally the largest part of the spectrum may thus become dark. Figs. 13 and 

 14 show how the absorption -bands appear in solutions of varying strengths: from 

 a i per cent, solution (above) the concentration progressively diminishes down- 

 ward by gradations of o.i per cent., until at O O the fluid is without hemo- 

 globin. The thickness of the layers of fluid is placed at i cm. 



Spectroscopic examination of small blood-spots, possibly for medico-legal 

 purposes, may be of the greatest importance. Often a minute spot is sufficient. 

 Dissolved with one or two drops of distilled water it may be introduced longitu- 

 dinally in a thin glass tube before the narrow slit of the spectroscope, and the 

 two bands of oxyhemoglobin appear. 



Preserved in alcohol, oxyhemoglobin is transformed into a modification in- 

 soluble in water but otherwise identical, namely parahemoglobin. 



