SOWING. 177 



Full air, a moderate degree of moisture, and a tem- 

 perature suitable to the kind of seed, are all neces- 

 sary to perfect germination. The heat of the soil at 

 seed time, whether in spring- or autumn, is generally 

 between 40 and 50 of Fahrenheit ; and this is suffi- 

 cient for corn and all other plants suited to the 

 British climate. 



By dissection and close inspection of the germina- 

 tion of seed, a pretty clear idea may be formed of the 

 process. A certain degree of humidity softens the 

 husk or shell : the constituents of air and water are 

 absorbed by the cotyledons, and with the excitement 

 of a necessary degree* of heat the whole swells ; the 

 rostell protrudes through the integuments, and pro- 

 ceeds or turns downward into the earth ; and soon 

 after the infant stem rises into the air. The seed is 

 matured by the parent by means of an umbilical 

 attachment or cord; but whether the new radicles 

 are an elongation of, or proceed from, this cord, the 

 writer has never been able to ascertain. 



The size of seeds determines the degree of com- 

 minution to which the surface soil should be reduced 

 to receive them ; and also the depth at which they 

 should be laid in. Large seeds, as those of the Spanish 

 chestnut, require to be embedded at the depth of one 

 and a half, or two inches ; whilst acorns, mast, and 

 other such sized seeds and corn, require a covering of 

 about one. This is a matter of more importance, and 

 requires a greater degree of care in the performance 

 than is commonly bestowed on it, especially in agri- 



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