42 ELEMENTARY PHYSIOLOGY. [ll. 



a light centre with a darkish rim : when 

 viewed in profile and the centre focussed 

 they appear somewhat dumb-bell shaped. 



d. They appear homogeneous, their colour is 



like that of the red blood corpuscles of the 



frog (cp. A. 1, c). 

 c. Towards the outside of the drop, where 



evaporation is going on, many of the red 



corpuscles are crenate. 



f. They are much smaller than the red corpus- 

 cles of the frog. Measure them (cp. A. 3). 



2. Observe the colourless corpuscles. They are 

 larger than the red, they resemble the white 

 corpuscles of the frog (A. 2, c. d. e.) ; to observe 

 their amoeboid movements a drop should be 

 protected from evaporation (A. 2, g) and, pre- 

 ferably, warmed to the temperature of the body. 



3. Irrigate with '5 p.c. acetic acid (cp. A. 4). 



a. The red corpuscles swell up and become 

 spherical, their haemoglobin is dissolved, 

 leaving the hardly visible stroma. (Effect 

 of water.) 



6. No nucleus is brought into view. 



c. The white corpuscles behave like those of 

 the frog (A. 4, a). 



4. Count the red corpuscles with Gower's haemato- 

 cytometer in the following manner. 



Fill the larger pipette with sodium sulphate 

 solution of Sp. Gr. 1025 up to the mark on the 



