72 



SOILS AND PLANT LIFE 



Place an equal amount of fresh seeds in a second bottle 

 and moisten them slightly to encourage germination. 

 Insert a thermometer into each bottle so that the bulb 

 rests among the seeds. The stem should extend out of 

 the neck of the bottle far enough to be read without dis- 

 turbing bottle or seed. Plug the neck of each bottle 

 firmly with cotton to prevent the escape of heat. A woolen 



Fig. 22. — Germinating seeds give off heat. 



cloth, wrapped carefullj' about each bottle, will serve to 

 keep the heat within the bottle and about the bulb of the 

 thermometer. Record the temperature in each bottle 

 every day during germination. All seeds used in this 

 exercise should b? first immersed for two hours in a solu- 

 tion consisting of one part of 40"^ formalin in 320 parts of 

 water. This will destroy the spores of molds. 



