HARMONIES OF VEGETATION. 257 



nate before it is properly matured, most seeds retain their living 

 principle for many years, if kept under proper circumstances. 



7. Light has been pronounced by some as necessary to 

 the process of germination, but it appears the presence 

 of this agent is rather injurious than requisite. 



Many plants originating from seeds, grow and come to perfection in 

 the darkest ruins and similar places. 



8. A certain degree of heat is indispensably ne- 

 cessary. 



During the severe weather of the winter season, the seeds which 

 have been placed in the earth do not germinate, but .remain inactive, 

 in a state perhaps very similar to the torpid condition of many 

 animals ; but on the coming on of the spring, the increased powers 

 of the sun, rouses the embryo from its slumbers, into animated life. 



9. Without an appropriate portion of humidity a 

 seed will not vegetate. 



10. The vast influence of air upon the vegetation of 

 the seed is very evident. No seed will germinate in 

 vacua. 



It is, no doubt, owing to the want of air, that seeds which are 

 placed very deeply in the ground, refuse to vegetate ; but they ger- 

 minate very readil y when the ground has been ploughed or turned up, 

 whereby they are more exposed to the action of the atmosphere. 



11. In order that seeds may readily germinate, it is 

 not only necessary, that they be exposed to the influence 

 of the air, but that the air is pure. 



Many experiments have plainly proved that the principa /agent to 

 forward germination is the presence of oxygen gas. Germination 

 I 2 



