RESPIRATION AND EXCRETION 299 



Special Reports 



1. The importance of fresh air for general health. 



2. Comparison of the human body or any animal body with a steam 

 engine. 



3. The source of energy in animals. 



4. The relation between muscular exercise and respiration. 



References 



Hunter, Essentials of Biology. Chap. XXVII. 

 Hunter, Elements of Biology. Chap. XXXIII. 

 Davison, The Human Body and Health (Advanced). Chap. XIII. 



PROBLEM LIII 



JL study of ventilation. 1 



Materials. A box of 7x10 inches base and 6 inches high 

 placed on a side and having 4 half-inch holes bored in each 

 end, and fitted with 

 corks. Have a pane of 

 glass to close the box. 

 Place two candles in the 

 box as shown in Figure 

 76. 



Method. Light one 

 of the candles so as to 

 use up oxygen. The 

 Candle will also give off FlG 75. Showing arrangement of box with 

 carbon dioxide, heat, glass front, for experiment in ventilation, 

 and water. Kemove the ( After Davison.) 



corks from one set of holes at a time, and observe the effects on 

 the burning candle. 



a. General Study 



Observations. 1. Place all the corks in. How long does 



the candle burn ? 



1 Adapted from Davison. 



