104 



SEEDS AND SEEDLINGS 



fresh air. Label it 5, and place it with the other four. The 

 water .used for soaking the seeds and for moistening the 

 bedding in this experiment should first have had its con- 

 tained air expelled by boiling. 



To test the behavior of seeds in the entire absence of 

 air is difficult, because it is not possible to expel all traces 

 of the atmosphere even with an air pump. 



140. Temperature. — Arrange some soaked seeds in 

 three or four different vessels just as in No. 2, in the first 

 experiment, and place where they will be subjected to dif- 

 ferent temperatures, ranging say from o" to 30° C (about 

 32° to 86° F.). Test frequently with a thermometer, keep- 

 ing the temperature as even as possible, and maintaining 

 an equal quantity of moisture in each vessel. Keep a 

 record of the number of seed sprouted in each after every 

 twenty-four hours. In those parts of the South whefe 

 the cold is not continuous enough to keep seed from ger- 

 minating under ordinary conditions, experiments in low 

 temperatures can not very well be made unless there is a 

 refrigerator available. In sections where there is continu- 

 ous cold, tests might also be made of the minimum tem- 

 perature at which different seeds will germinate. Sachs 

 found the minimum for corn to be 9°.4 C. (about 49° F.), 

 and for the gourd, 14" C. (about 58° F.). 



141. Recording Observations. — Arrange a page of your 

 notebook after the model given below, and record your 



Number of Seeds Germinated 



