SCIENCE OF COMMON THINGS. 235 



Necessity of cleanliness. Color of the blood. 



157*0 Do we respire or absorb and expel oxygen in any oilier way than, 

 through the lungs ? 



We breathe also in a degree through the pores of 

 the skin, absorbing oxygen and expelling carbonic acid. 



157*1 Do extensive burns on the surface of tht body frequently produce 

 diseases of the lungs f 



They do. 



157*3 Why should extensive burns on the surface of the, body tend to 

 produce diseases of the lungs ? 



While in a condition of health, the skin tranquilly 

 aids the lungs in the expulsion of carbonic acid from 

 the body ; but the portion of the skin which has been 

 scorched by an extensive burn, no longer being able to 

 perform that function, the lungs are obliged to assume 

 an extra duty, and suffer as a consequence of their 

 exertion. 



157*3 //j by neglect of washing, we suffer the sJcin to become covered with 

 impurities, do we not disturb the healthy action of the system f 



We do ; there is no better-established law of health, 

 than that the surface of the whole body should be kept 

 clean and free from all impurities. 



157*4 If the carbon taken from the system through the agency of the 

 lungs be not t estored, what is the consequence ? 



Starvation ensues. 



157*5 How does the oxygen we inhale mingle with the blood? 



The oxygen of the air is absorbed in the lungs by the 

 blood, and imparts to it a bright red color. 



157*6 How does oxygen convert the color of blood into a bright red f 



The coloring matter of the blood is formed by very 

 minute globules floating in it. The oxygen uniting 

 with these globules changes their color, to a bright red. 

 The blood contains iron, and this metal is supposed to 

 play an important part in the coloration of the blood. 



157*7* What color is the blood before it is oxidized in the lungs ? 



A dark purple ; the oxygen turns it to a bright red* 



157* S Do plants respire as well as animals t 



They do; and their leaves may be regarded as per- 

 forming for them similar offices as the lungs of animals. 

 They are the breathing organs of plants. 



