THE BLOOD 



71 



The counting chamber is cleaned with distilled water and nothing rougher than a 

 camel's-hair brush. Do not use alcohol or ether. 



6. Enumeration of the White Corpuscles. Proceed as before, but 

 dilute the blood with a 1 per cent, solution of acetic acid. This agent 

 destroys the red corpuscles. The dilution usually made is 1 : 200. 



Mb 



on 



So 



10 o" l 



o - on 



FIG. 44. HEMOCYTOMETER. (Thoma-Zeiss.) 



A, Pipet; B, glass bead; C, counting chamber seen from side; D, counting chamber seen 

 from above; E, field as seen under microscope. 



7. Hemorrhage. Remove the clip from the carotid artery and allow 

 the blood to escape into a tall beaker. Notice the differences in the 

 force of the flow and the changes in the character of the respiratory 

 movements, resulting in consequence of the progressive anemia and 

 insufficient aeration of the tissues (hemorrhagic dyspnea). Kill the 

 animal by giving an excessive amount of ether. 



Place the beaker with the blood in a cool place and allow it to stand 

 for twenty-four hours. Study the appearance of the serum and coag- 

 ulum at the end of this period. 



