

CHAPTER XX 
THE BEHAVIOUR OF PLANTS TOWARD LIGHT 
Compare plant stems grown in sunlight with those 
grown in darkness. When planting seeds of the gup- 
flower, marrow, buckwheat, pea, wheat, or maize, ete., 
place some of the pots under tight boxes 
to exclude the light. The pots should be 
covered as soon as the seeds are planted so 
that no light will reach the young 
seedlings. 


They should remain 

covered for two or 
three weeks or more. 
They can be safely 
uncovered occasion- 
ally, for a few mo- 
dee 
pe 
aig 
supply the necessary 
water and to compare 
them with the seed- 
7 Imes started at the 
FG. 164, Marrow Seedlings: one at left grown in same time, in the 
dark, one at right of same age grown in light, ; 
| heht. 
Observe the Plants about twice each week. Make 
Measurements of the growth; sketch, and keep a 
136 
ments at a time, to 
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