CHANGES IN COLOR OF BLOOD. 



131 



The changes that take place in the color of the blood, both 

 in the lungs and in the tissues of the other parts of the body, 

 may be illustrated as follows : Prepare a heart as directed on 

 page 64. Use for the liquid a strong solution of litmus, neu- 

 tralized or slightly alkaline ; place in the throat of each fun- 

 nel a small sponge. Saturate with ammonia the sponge in the 

 funnel representing the capillaries of the body, and saturate 

 the one in the funnel representing the capillaries of the lungs 

 with hydrochloric acid. 



OPEN AURICULO-VENTRICULAR VALVES 



<*3S?S6< 



Fig. 49. Diagram of the Circulation of Blood. (Dorsal View.) 



Now, on working the heart the liquid will change from red 

 to blue in the funnel representing the body, and from blue to 

 red in the funnel representing the lungs. 



" Anatomically there are two lungs, and the heart lies be- 

 tween them; physiologically, the lungs form a single organ, 

 which is interposed between the two hearts." WILDER. 



