DIGESTION, CIRCULATION, AND ABSORPTION 281 

 References 



Hunter, Essentials of Biology. Chap. XXV. 



Hunter, Elements of Biology. Chap. XXVIII. 



Davison, The Human Body and Health (Advanced), pp. 98, 99, 108. 



PROBLEM XLVIII 



To study the general composition of blood. 



Materials. Fresh frog's blood or blood from the finger. 

 Slides, cover glasses, portable compound microscope, or com- 

 pound microscopes set in various parts of the laboratory for 

 inspection by the pupils under direction of the instructor. 



a. The Corpuscles 



Note. Observe that the blood is composed of two com- 

 ponents, solid bodies (corpuscles) and a liquid (plasma). Some 

 of the corpuscles are disklike, and some globular and granular, 

 while the plasma is the liquid in which the corpuscles float. 



Observations. 1. What is the color of the corpuscles you 

 most readily see ? What is their shape ? Note. These are 

 red corpuscles. 



2. Do you find other corpuscles, globular in shape and 

 more transparent ? (Difficult to see.) Note. These are white 

 corpuscles. 



3. What is the appearance of the plasma ? 



Conclusions. 1. Do you think that the functions of the two 

 kinds of corpuscles are the same ? That is, do special functions 

 imply special structures? 



2. Why does the blood appear red? 



3. What have you already learned must be in the blood 

 plasma? 



4. What is an evident function of the plasma? 



Questions 



1. What service do the red corpuscles render? The white 

 ones? 



