THE RED CORPUSCLES 157 



LABORATORY EXPERIMENTS FOR THE EXAMINATION OF 



THE BLOOD. 



1. Microscopical Examination of the Blood. Mount a drop of frog's 

 blood in o . 7 per cent, sodium chloride and examine with the high power of a 

 compound microscope. The red corpuscles will appear as oval nucleated 

 discs with a faint yellowish color, figure no. Here and there white granular 

 cells of irregular outline will be noted, the white corpuscles. Examine the 

 drop of blood with a high magnifying power (oil-immersion lens) and 

 sketch the outline of the blood-cells. Select the white corpuscle which is 

 most irregular in outline and make a series of outline drawings once every 

 minute to show its ameboid movements, figure 117. 



Draw a drop of your own blood by puncturing the tip of the finger, under 

 sterile conditions, and mount in a drop of o . 9 per cent, physiological saline. 

 Examine with a high power, note the small biconcave red corpuscles which 

 appear faintly yellow in color and even adhere in rouleaux, figure 109. The 

 white corpuscles will appear as somewhat larger granular discs differing in 

 form and size. By mounting a drop of blood on a warm stage the ameboid 

 movements of the white corpuscles can be observed with comparative ease. 



2. Action of Fluids on the Red Corpuscles. Water. When water is 

 added gradually to frog's blood, the oval disc-shaped corpuscles become 

 spherical and gradually discharge their hemoglobin, a pale, transparent 

 stroma being left behind. Human red blood-cells change from a discoidal 



FIG. 126. FIG. 127. FIG. 128. FIG. 129. 



FIG. 126. Effect of Hypertonic Salt Solution on the Red Blood Corpuscles of Man. 

 PIG. 127. Effect of Acetic Acid. FIG. 128. Effect of Tannin. FIG. 129. Effect 

 of Boric Acid. 



to a spheroidal form and discharge their cell contents, becoming quite trans- 

 parent and all but invisible (ghost corpuscles). 



Hypertonic Salt Solutions. Mount a drop of human blood in 2 per cent, 

 sodium- chloride solution. The red blood-cells lose their disc shape and be- 

 come spherical with spinous projections or crenations, figure 126. 



The original form of the red blood-cells can be restored by transferring 

 them to isotonic salt solution. 



Dilute Acetic Acid. This reagent causes the nucleus of the red blood- 

 cells in the frog to become more clearly defined; if the action is prolonged, 

 the nucleus becomes strongly granulated, and all the coloring matter seems 

 to be concentrated in it, the surrounding cell substance and outline of the cell 

 becoming almost invisible; after a time the cells lose their color altogether. 



