GERMINATION OF SEEDS 23 



around the root as a marker instead of using drawing ink. Keep the 

 sprouted grain moist by placing it in damp sand or between moist 

 blotting papers kept either in a small tight box or between two saucers. 

 After a day or two measure the distance between the two marks, which 

 you will find to be unchanged. Now measure from the outer mark to 

 the tip of the root and you will find that this portion has grown 

 rapidly. 



Roots of all plants increase in length only near the tips. 

 However, if you make measurements of the stems of young 

 plants, you will find that all parts of the young stem, as 

 well as the tip, increase in length until a certain age is 

 reached. 



Moisture necessary to make seed sprout. Did anybody 

 in this class ever plant seed when the ground was dry and 

 when no rain fell soon afterwards ? Did any seed come 

 up ? You can prove that seeds need moisture in order to 

 germinate, by planting some seeds in two tomato cans in 

 the window ; keep the soil in one can very dry and in the 

 other barely moist. What happens ? 



Heat required for germination. Oats that were sown 

 during very cold weather have sometimes remained un- 

 sprouted for a month. When the sowing was done in 

 warmer weather, they came up in about one third of that 

 time. Seeds of different plants require very different 

 amounts of heat to wake them and make them sprout or 

 germinate. Seeds of wheat, oats, rye, and barley germinate 

 when the soil is quite cool, and so the farmer sows these 

 crops during the colder part of the year. Corn grains 

 require more heat than oats, but less than the seeds of 

 cotton, cowpeas, or peanuts. A farmer never plants these 

 last crops until the soil has become somewhat warm. 



