THE SEED AND ITS GERMINATION 9 



germination, we find that the principal ones are heat, 

 moisture, and presence of air. A few simple experiments 

 will show what influence these conditions exert. 



8. Temperature. — Common observation shows .that a 

 moderate amount of warmth is necessary for the sprout- 

 ing of seeds. Every farmer or gardener knows that 

 during a cold spring many seeds, if planted, will rot in 

 the ground. But a somewhat exact experiment is neces- 

 sary to show what is the best temperature for seeds to 

 grow in, and whether variations in the temperature make 

 more difference in the quickness with which they begin 

 to germinate or in the total per cent which finally succeed. 



EXPERIMENT I 



Relation of Temperature to Germination. — Prepare at least four 

 teacups or tumblers, each with wet soft paper packed in the bottom 

 to a depth of nearly an inch. Have a tightly fitting cover over each. 

 Put in each vessel the same number of soaked peas. Stand the ves- 

 sels with their contents in places where they wiU be exposed to dif- 

 ferent, but fairly constant, temperatures, and observe the several 

 temperatures carefully with a thermometer. Take pains to keep the 

 tumblers in the warm places from drying out, so that their contents 

 will not be less moist than that of the others. The following series 

 is merely suggested, — other values may be found more convenient. 

 Note the rate of germination in each place and record in tabular 

 form as follows : 



No. of seeds sprouted in 24 hrs. 48 hrs. 72 hrs. 96 hrs. etc. 



At 32°, ^— . 



At 50°, — — 



At 70°, 



At90°i 



1 For the exact regulation of the temperatures a thermostat (see Handbook) 

 is desirable. If one is available, a, maximum temperature of 100° or over 

 should be tried. 



