THE PHYSIOLOGY OF SOWING SEEDS. 597 
are of no avail, since the primary change whereby 
the germ is enabled to exert its vital energy upon 
the matter around it, is prevented from taking 
place. Hence seeds at the bottom of stagnant 
waters, hence seeds in swampy soils, hence seeds 
deep buried below the surface of the ground, or 
shut up in hard clods, being cut off from the 
action of the air, remain dormant. The great 
supporter of all life is absent; and, therefore, 
proper material and proper conditions for aiding 
and maintaining vital action are vain and useless. 
The healthy germination of all seeds depends 
then, upon a due and adequate accession of air. 
In order to secure this accession of air, as com- 
plete a pulverisation of the soil, as possible, 
becomes necessary ; and also as slight a covering 
of the seed, within the soil, as is consistent with 
keeping the seed, during germination, from the 
retarding influence of light. Light checks the 
vital chemical action within the seed, whereby 
the farinaceous substances are converted, from 
an inert mass, into living, growing tissues. And 
deep burying the seed causes the blade sent up 
by germination to the surface of the soil, to 
become so attenuated by an expenditure of the 
material of the seed to enable the blade to reach 
4 Xk 
