GERMINATION OF SEEDS 67 



Method. Fill one flowerpot with dry seeds and the other 

 with soaked seeds of the same kind. 



Compare the thermometers to be sure that they read alike. 



Thrust a thermometer into the center of each pot and 

 stand them side by side, covering each flowerpot with a 

 cloth to prevent evaporation, but permitting the stems of 

 the thermometers to project above the covering. 



After a few hours compare the readings of the two instru- 

 ments. 



Note. A differential thermometer can be used if one is at hand 

 and the comparative temperatures noted. 



Note. The heat in this experiment may not be entirely due 

 to the germination of the seeds. Bacteria of decay often cause 

 the evolution of considerable heat. If the seeds are moistened 

 first with a solution of 5 per cent formalin and then are thoroughly 

 rinsed off in clear water, they will be far less likely to become heated 

 through agency of bacteria and the experiment will be more exact. 

 For use in high schools, however, this precaution is hardly neces- 

 sary. 



51. EFFECT OF LIGHT 



Object. To find out whether light has any effect 

 upon germination of seeds. 



Apparatus. Two tumblers, sawdust, seeds, and a dark box. To 

 make a dark box blacken a chalk box inside with ink or paint. 

 Cover the outside with one or two coats of black paper or cloth so 

 that no light can enter. 



Method. Prepare the seeds by planting them in damp 

 sawdust in the tumblers. Then put one tumbler in the 

 dark box and the other outside. Place both on a window 

 sill where they will receive the sunshine and move them from 

 time to time so that the uncovered glass shall have plenty 

 of light. Keep both tumbler and dark box close together 



