
GROW fie 133 
The following experiments illustrate the conditions under 
which growth takes place : : 
Take some seeds, soak in cold water, and 
plant either in sawdust or cocoanut fibre. Leave 
for a few days. | 
Put some other seeds in boiling water and treat as above. 
After a few days the seeds soaked in cold 
water will be found germinating. Those put first 
in boiling water will show no signs of germination or of life ; 
they are, in fact, dead, having been killed by the boiling water. 
Growth is poe only when the plant is 
Experiment I. 
Result. 
Conclusion. 
living. 
Take two seedlings. ee one (A) care- 
Experiment II. : 
fully every day, but do not water the other (B). 
Result. A grows, B does not. 
Conclusion. Water is necessary for growth. 
Take two growing beans, suspend from corks 
of two jars (Fig. 12). Put a little water at 
the bottom of one jar (A), so that the roots are in moist air, 
whilst in jar B the water covers the cotyledons. 
The plant in jar A grows much faster than 
that in jar B. 
Plants grow best when exposed to free 
oxygen. This experiment also shows the 
necessity of a certain amount of water for a plant, and the 
disadvantage of overwatering ; it explains, too, why draining 
Is necessary. 
Experiment III. 
Result. 
Conclusion. 
Take two air-tight jars, to the cork of each 
of which a moist sponge on which cress seeds 
have been sown is fastened. | 
In the bottom of one jar there should be a little water, in 
the other pyrogallic acid, which takes the oxygen out of the air. 
The seeds will not grow in the jar with pyro- 
gallic acid. 
As pyrogallic acid has taken the oxygen out 
of the air in the jar, it is clear that oxygen | is 
necessary to growth. 
Experiment IV. 
Result. 
Conclusion. 
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