260 THE HUMAN BODY. 



thorough whipping with the bundle of wire. Half fill each bottle 

 with the defibrinated blood; then cork the bottles. 



d. Having brought home all the specimens, set them aside until the 

 next morning in a cool place. It will then be found that the blood 

 in each bottle is dark-colored or venous (having used up its own 

 oxygen and not being able to get more from the air), and that the 

 clot in the jar is bright scarlet (arterial-colored) above where it is in 

 contact with the air, but dark purple-red where it is immersed in 

 the serum. 



e. Invert the clot : in an hour or two its previously dark original 

 under surface will have become bright red, while the original upper 

 surface, previously bright-colored and now immersed in the serum 

 away from the air, will have become venous in tint. 



/. Take the cork out of one bottle; renew the air in it by blow- 

 ing. Placing a thumb on the neck of the bottle, thoroughly shake 

 up the blood with the air. Then renew the air again, and shake once 

 more; and so on for three or four times. At the end the blood shaken 

 up with air will be seen to have assumed a much brighter red color 

 than that kept shut up in the other bottle. 



<7. If the proper chemical apparatus and reagents are accessible, 

 the air in the bottle about to be shaken may be replaced by nitrogen, 

 hydrogen, or pure oxygen, and the procedures described in section 

 / repeated. It will be found that only the oxygen brightens the 

 blood color. As any one possessing the chemical apparatus and 

 knowledge implied for the execution of this experiment will certainly 

 know how to replace the air by the gases above named, no further 

 details need be given. 



