LESSON ITT. 



BLOOD CORPUSCLES OF MAK 

 STRUCTURE. CO UNTING. 



1. With a sharp needle prick the finger either 

 at the tip, or a few millimetres from the root of the 

 nail (the finger should be perfectly clean) ; touch with 

 the centre of a cover-slip the drop of blood which 

 issues ; lower the cover-slip on a slide. Observe the 

 red corpuscles. 



a. They roll about readily when the cover-slip is 

 lightly touched. Soon after being taken from the 

 body they stick to one another, and, owing to their 

 shape, usually in rouleaux. 



b. They are biconcave discs. Note that on focus- 

 sing down on the circular face a darkish centre and a 

 light rim is first seen and then a light centre with a 

 darkish rim : when viewed in profile and the centre 

 focussed they appear somewhat dumb-bell shaped. 



c. They appear homogeneous, their colour is like 

 that of the red blood corpuscles of the frog (cp. 

 Less. II. 1, c). 



