62 



SEEDS CAN NOT GERMINATE WITHOUT AIR 



germinate in the packed soil because the air was largely 

 shut out by the too wet and too closely packed soil. 



Wet Clayey Soil 

 Excludes Air. 

 Clayey soil so wet 

 that, with slight pres- 

 sure, it becomes like 

 soft putty, is too wet 

 to plant seeds in. Al- 

 though the seeds can 

 absorb water rapidly 

 from such a soil, they 

 rarely germinate well 

 in it, for, if it is left 

 loose over the seeds, it 

 dries out quickly, and, 



if it is packed around 



FIG. 29. Roots need air. them, it shuts OUt tOO 



much air. Planted seeds should not be watered so often 

 as to keep the spaces in the soil filled with water. 



QUESTIONS AND EXERCISES. 



1. Why did not the grains of wheat germinate under 

 water? 



2. Name some kinds of seeds that germinate under water. 

 From where do they get the air? 



3. Name three things necessary for germination. 



4. Seeds germinate most quickly in a moist, warm, sandy 

 soil. Why will they not germinate so quickly in a moist, 

 warm, clay soil? 



