DIRECT SOWING. 151 



In the case of partial sowing the quantity of seed is 



proportionately smaller, thus for 



Sowing in strips, furrows, 



or trenches about 65 — 70 % of broadcast sowing. 

 ,, ,, patches . . 50 ,, ,, ,, 



,, ,, pits or holes . 25 — 35 ,, ,, ,, 



4. Conditions of Germination. 



The process of germination is as follows : — 

 (1.) Swelling of the seeds. 

 (2.) Chemical change of the nourishing substances 



deposited in the seed. 

 (3.) Development of the embryo. 

 The swelling of the seed is due to the absorption of water. 

 If then a sufficient amount of heat and oxygen are available, 

 the reserve materials are changed into soluble substances fit 

 for the formation of new cells ; growth then sets in, which 

 causes an enlargement of the embryo followed by the bursting 

 of the shell of the seed and the protrusion of the rootlet. 



The conditions for the successful germination of forest 

 seeds are thus : — 



(1.) A constant but moderate supply of water. 



(2.) A temperature not lower than 45°, but better from 



55—75° Fahr. 

 (3.) Admission of air, whence the oxygen is derived. 

 The presence or absence of light is of no importance. 

 These conditions can easily be provided in the case of 

 small experiments, but in operations conducted on a large 

 scale they can only to a certain extent be secured by a 

 suitable condition of the germinating bed, by the manner 

 of covering the seed, and by sowing at the most suitable 

 time of year. 



a. The Germinating Bed. 

 A suitable condition of the germinating bed is of prime 

 importance ; it is secured by working or loosening the soil, in 



