40 ELEMENTARY PHYSIOLOGY. [ll. 



substance is seen which often stretches out 

 to the periphery of the corpuscle in the form 

 of a star. The nuclei of the colourless cor- 

 puscles also stain deeply. 



6. Place several very small drops of blood two or 

 three mm. apart on a slide and leave for a few 

 minutes, then cover with a cover-slip, and put 

 under a high power. Take a little blood from a 

 freshly killed frog and establish a current under- 

 neath the cover-slip from one side of it to the 

 other (cp. 4). The first small drops will have 

 partially clotted and will serve as an imperfect 

 barrier to the corpuscles in the current ; in such 

 places note that the shape of the red corpuscles 

 is easily changed and recovered, and that the 

 colourless corpuscles stick to one another and to 

 the glass more than do the red. After the 

 current has passed a short time largish clumps 

 of colourless corpuscles will be seen. 



7. Having destroyed the brain and spinal cord of a 

 frog, expose the heart and cut it across, suck up 

 a little blood in a clean pipette and add it to 

 about five times its volume of 2p.c. boracic acid, 

 stirring gently. Mount a drop of the mixture at 

 once and observe the red corpuscles with a high 

 power. 



The nuclei scarcely visible at first become in a 

 short time rather deeply stained with haemo- 

 globin ; small spheres of hemoglobin appear also 

 in the body of the corpuscle ; occasionally the 

 haemoglobin may appear to stretch in rays from 



