No. fi. DEPARTMENT ( >F AC KKlII/rH HE. 345 



eiple applies to all animal life. Ass there are limits beyoud whicli 

 auimal life can not exist, so there are limits of temperature beyond 

 wliioh vegetable life will wither and die; and as there is a so-called 

 normal temperature, whicli is the best temperature for the par- 

 ticular kind of animal, so there is a temperature at which plant 

 development will take place to the best advantage. The limits in 

 case of the hatter are, however, much further apart. Many of the 

 changes which occur in the plant and animal, human or otherwise, 

 are chemical changes. "When wood burns or when a lamp is lighted, 

 a chemical change takes place; the oxygen of the air is uniting 

 with it. Before this change can begin to take place, however, the 

 wood must first be ignited; that is, its temperature must be raised 

 to a certain point and Avhen this is once done, other conditions 

 being favorable, the material continues to burn. There is sufficient 

 heat produced by the change taking place to maintain the action. 



The germination of a seed partakes of the same nature. It must 

 unite with the oxygen of the air in order that its vital principles 

 mav become manifest. It is, therefore, necessarv that the tern- 

 perature of the soil be raised as nearly as possible to the point at 

 which this action will proceed to the best advantage. The mini- 

 mum temperature at which most seeds will begin growth is about 45 

 degrees Fahrenheit, but the best results are brought about by a 

 temperature of 68 to 70 degrees. This best temperature will, of 

 course, vary with the particular Icind of seed. It has been found 

 by experiment that oats will germinate in three days at a tempera- 

 ture of slightly over G5 degrees, VRhile wdtli the temperature as low 

 as 41 degrees, seven days are required for germination. In the 

 same way, corn which will germinate in three days at 05 degrees, 

 requires eleven days if the temperature is down to 51 degrees. The 

 desirability of having the soil warmed early in the spring is there- 

 fore apparent. 



While in the animal body, danger is usually to be apprehended 

 from too high a temperature, in the vegetable world the reverse is 

 true. It may seem to many that if a temperature of 65 to 70 

 degrees is best suited for the germination of seeds that this tem- 

 perature would not be difficult of attainment and that the soil 

 would easily become this wai-m. Observation of soil temperature, 

 conducted at the Experiment Station show that the average tern 

 perature of the soil at the surface and a depth of one and three 

 inches, and extending through several years was as follows: 



2:? 



