8 LAND DRAINAGE 



The days indicated under the several temperatures, 

 and after the seeds, undoubtedly indicate the time re- 

 quired for the radicle to burst through the coat of the seed, 

 not the time required for the radicle to appear above 

 ground. (See Fig. 4.) 



More recent investigators assert that some of these 

 seeds do germinate occasionally at temperatures lower 

 than those indicated in the above tables. The late 

 C. F. Wheeler found that chess seed would germinate when 

 lying on a cake of ice in a refrigerator, and send roots f 

 inch into the ice. Wheat and other grains are not infre- 

 quently sown, in the Northwest, when the soils are 

 thawed but six or even four inches deep in the spring; 

 they germinate in a short time, long before the frost has 

 entirely disappeared below the seed-bed. In such cases, 

 the seed-bed possesses a temperature much above that 

 of the frozen ground below. 



11. Desirable temperature condition. The best and 

 most desirable temperature is one ranging from 70 to 

 90 F. The question that should be uppermost in the 

 farmer's mind is not " at how low temperature will seed 

 germinate/' but rather "what means may T employ to 

 bring the temperature of the seed-bed to most nearly 

 approximate the ideal ? " In Fig. 2 are shown the 

 effects of temperature on germination. The three j ars were 

 prepared alike, and each had ten kernels of corn, from the 

 same ear, planted in it. The jars were then placed one 

 in a temperature of 55 F., one in a temperature of 70 F., 

 and one in a temperature of 85 F. The photograph was 

 taken on the eighth day from planting. 



12. Later effects. If, on the eighth day, the jars 

 shown in Fig. 2 were placed together, and allowed to remain 

 in a temperature of 75 to 85, most, probably all, of the 



