BLOOD 



197 



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be continued for hours before natural breathing is 

 restored. 



Diseases of the Respiratory Tract. — The most common 

 of these diseases is a cold located in the nose and throat. 

 The nasal passages be- 

 come clogged with 

 mucus which contains 

 many germs. These 

 germs are widely distrib- 

 uted in sneezing. 



Diphtheria is a germ 

 disease which is located 

 in the throat and nose. 

 For many years diph- 

 theria was one of the 

 most deadly of our dis- 

 eases, but through the 

 use of the diphtheria 

 antitoxin the danger has 

 been greatly reduced. 



Tuberculosis of the 

 throat and lungs is a 

 widely distributed dis- 

 ease which causes many 

 deaths each year. See 

 page 235. 



158. Blood. — The blood is the fluid which circulates 

 through the heart, arteries, and veins, supplying nutritive 

 material to all parts of the body. Blood is made up of a 

 fluid (plasma) which contains cells or corpuscles ( Latin, 

 corpuseulum, little body). The blood cells or corpuscles 

 are of two kinds, red and white. 



The red corpuscles are colored with a substance called 

 haemoglobin (he-mo-glo'bin: (iivek, haima, blood: globus, 



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Figure 210. — Steam Heating. 

 By Earl Hallenbeck. 



