40 OUTLINES OF FORESTRY. 



thirty feet below the surface of the earth, at the bottom of a 

 barrow which was opened near Dorchester. He had been 

 buried with some coins of the Emperor Hadrian, and it is 

 therefore probable that the seeds were sixteen or seventeen 

 hundred years old." 



" It has already been seen that under certain circumstances, 

 the vitality of seeds may be preserved for a very considerable 

 length of time ; but it is difficult to say what are the exact 

 conditions under which this is effected. We learn from ex- 

 periment that seeds will not germinate if placed in vacua, or 

 in an atmosphere of hydrogen, nitrogen, or carbonic acid ; but 

 no such conditions exist in nature, and, therefore, it cannot 

 be they which have occasionally preserved vegetable vitality 

 in the embryo plant for many years. Perhaps the following 

 remarks, in a work lately published by the Society for the 

 Diffusion of Useful Knowledge, may throw some light on the 

 subject : 



" It may, upon the whole, be inferred from the duration of 

 seeds buried in the earth, and from other circumstances that 

 the principal conditions are, 1, uniform temperature ; 2, mod- 

 erate dryness ; 3, exclusion of light ; and it will be found 

 that the success with which seeds are transported from foreign 

 countries, in a living state, is in proportion to the care and 

 skill with which these conditions are preserved. For exam- 

 ple, seeds brought from India, round the Cape of Good Hope, 

 rarely vegetate freely : in this case the double exposure to the 

 heat of the equator, and the subsequent arrival of the seeds 

 in cold latitudes, are probably the causes of their death ; for 

 seeds brought overland from India, and therefore not exposed 

 to such fluctuations of temperature, generally succeed. Others, 



