XIV. RESPIRATION 



A. Anaerobic Respiration: 



Experiment 36. To illustrate anaerobic respiration. 



1. Remove the seed-coats from three or four pea seeds 

 that have soaked in water over night. 



2. Fill a large glass test-tube with mercury, and 

 invert it in a bath of mercury. 



3. Place the pea seeds under the mouth of the inverted 

 test-tube, and allow them to float to the top. Use 

 every possible precaution to prevent air being car- 

 ried up with the peas. Can the presence of air 

 be entirely prevented? 



4. Securely fasten the test-tube in the inverted posi- 

 tion, with its mouth under the surface of the mer- 

 cury in the bath, and during the next twenty-four 

 to forty-eight hours observe the formation of 

 gas, which replaces the mercury around the seeds. 



5. Now introduce into the test-tube with the pea seeds 

 a small piece of potassium hydroxide. If the gas 

 given off by the seeds is CO 2 it will be absorbed by 

 the potassium hydroxide, and the mercury will rise 

 in the tube. 



6. Do these seeds respire under strictly anaerobic con- 

 ditions? Discuss, in your note-book, all the pros 

 and cons, and endeavor to make a clear statement 

 of just what this Experiment does and does not 

 demonstrate. 



B. Aerobic Respiration: 



Experiment 37. To demonstrate what exchange of 

 gases accompanies the aerobic respiration of a living 

 plant. 



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