202 SUGAR BEET SEED. ] 



when the average temperature of the soil remains about 

 7 degrees C. (^7.6 degrees F). 



Air. 

 When we consider that nearly one-fourth of 

 the total vegetable earth is air, it becomes evident what 

 an important role air plays. Therefore, certain precau- 

 tions must be taken to sufficiently work the soil, so that 

 the air circulation is not too free, as it would soon evap- 

 orate all the moisture, and thus do more harm than 

 good. Evidently, without oxygen, seed cannot ger- 

 minate. During the action of heat and moisture, life 

 cannot exist unless there is oxygen to help the plant; 

 during its feeding process the albumen at the disposal 

 of the germ cannot undergo the requisite transforma- 

 tion. That certain microscopic organisms help this 

 transformation, there is not the slightest doubt. Mois- 

 ture carries these ferments into the centre of the 

 embryo and the action of the diastase completes the 

 first stages of plant development. Experiments have 

 been made with the view to substituting other gases for 

 air, but they led to very secondary results. 



Light. 

 As soon as the young leaves appear above 

 ground, light has an important part to play. The 

 chlorophyll then brings about the interchange of cer- 

 tain gases, and, furthermore, helps to decompose or to 

 transform those elements of which the vegetable organ- 

 ism is made up. These chlorophyll granules, which 

 consist of green-colored protoplasm, bring about 

 these changes which result in starch formation, which 

 will be subsequently distributed through the root. 

 The chlorophyll, separating the carbon from the car- 

 bonic acid taken from the air, liberates the oxygen 

 absorbed and supplies the carbon to form a carbo- 

 hydrate, such as starch, by combining with the hydro- 

 gen and oxygen of the water of the soil taken up by 



