THE BLOOD. 



223 



Ex. Beat up 100 cc. of the blood thoroughly, cool to a low temperature 

 and add 10 cc. of ether and a little water. Shake this mixture thoroughly 

 and allow it to stand on ice over night. Filter on porous paper, squeeze 

 out the mother-liquor as far as possible, dissolve in a little water, filter 

 again and to the new filtrate add one-fourth its volume of alcohol, mean- 

 while stirring constantly. Allow the mixture to stand to crystallize. An 

 illustration is given of the usual forms. 



A simple test may be also made by mixing a drop of dog's blood with a 

 drop of water on a slide and allowing it to partly evaporate. A cover 

 glass is then put on and the crystals are looked for with the microscope. 



The conditions of com- 

 bination between hemo- 

 globin and oxygen have 

 been studied by several 

 authors. It has been 

 found that by exhausting 

 blood under the air pump 

 the greater part of the 

 oxygen becomes free. It 

 has been found further 

 that I gm. of hemoglobin 

 may be made to take up or 

 give off something over 

 1.3 cc. of oxygen. This 

 reduces to 2 atoms of oxy- 

 gen for i atom of iron 

 present in the hemoglobin. 

 Various chemical agents 

 have the same effect. In 

 the case of certain solu- 

 tions the action is a chem- 

 ical one, while with sev- 

 eral inert gases the action is physical. 



These reactions are accompanied by a change of color in the 

 oxyhemoglobin or blood solution experimented upon. Oxy- 

 hemoglobin solutions show a brighter red color than do those 

 containing the reduced hemoglobin. This difference is well 

 illustrated in the contrasting shades of arterial and venous 



FIG. ii. Crystals of hemoglobin, a and 

 b from human blood ; c from the cat ; d 

 from the guinea-pig ; e from the marmot ; 

 / from the squirrel. 



