II] BLOOD CORPUSCLES OF FROG 11 



microscope with a low power 1 and observe the numer- 

 ous corpuscles floating in the plasma. 



Examine it with a high power 1 and observe the 

 red corpuscles ; if a large drop of blood has been 

 taken the corpuscles will overlap one another, in which 

 case another preparation should be made with a smaller 

 drop. 



a. The red corpuscles are flattened ellipsoids ; note 

 their spindle shape when seen on edge as they roll 

 over. The great majority are of the same size and tint. 



b. They appear at first homogeneous, but soon a 

 certain number show a central paler oval nucleus. 



c. A single corpuscle is pale yellow ; the colouring 

 substance (haemoglobin) is equally diffused throughout 

 it ; when several corpuscles lie over one another they 

 together appear red. 



2. Examine the colourless corpuscles in parts 

 of the specimen where the red are not very numerous. 



a. They are much fewer than the red. They are 

 smaller than the red, but they vary in size. 



6. They are usually spherical, when first mounted, 

 but soon many of them put out processes and become 

 irregular in form. 



c. The majority have no distinct granules (hyaline 

 corpuscles). Some have comparatively large and re- 

 fractive granules; these are the coarsely granular 

 corpuscles. The nucleus in these cells can seldom be 

 made out (cp. 15). 



1 In later sections low power and high power are abbreviated to 

 (1. p.) and (h. p.). 



