54 ANATOMY AND PHYSIOLOGY 



1. Place a vigorous potted plant on a ground-glass 

 plate. By the side of it place a watch-glass full of 

 lime water, or baryta water; over all place a glass 

 bell-jar with a large tubulature at the top. 



2. Make the joint between the bell-jar and the ground- 

 glass plate air-tight by means of vaseline. 



3. Test the air in the jar with a lighted taper to be sure 

 that it contains enough oxygen to support combus- 

 tion. 



4. Insert a rubber stopper into the tubulature so as 

 to make it air-tight, and set the plant aside, in a 

 dark place. Why? 



5. At the next laboratory period (preferably on the 

 following day), and without disturbing the bell-jar, 

 observe the color of the lime water in the watch- 

 glass. What does it indicate? 



6. Quickly and cautiously insert a lighted taper into 

 the bell-jar through the tubulature. What results? 

 What inference is justified? 



Experiment 38. To see if all parts of a plant, and non- 

 green plants, respire. 



7. Take six cylindrical glass jars, a, b, c, d, e, and /, 

 provided with air-tight rubber stoppers. 



8. Into (a) place a quantity of green leaves; into (b) 

 green stems of some herb; into (c) young clean 

 roots of some herb; into (d) freshly picked flowers; 

 into (e) one or two fresh fleshy fungi; and into (/") 

 nothing. Confine the plant material to one side 

 of the jars by inserting a vertical partition of coarse 

 wire netting. 



9. Test the air in each jar to be sure that it will sup- 

 port combustion, then cork the jars air-tight, and 

 place them in a convenient place. 



10. At the next laboratory period carefully test the air 



