OF SEED-PACKING. 181 



vii. 922,) show that carbonic acid is formed by the as- 

 sistance of the oxygen obtained by the decomposition 

 of water. 



If we apply these considerations to the plans usually 

 employed for preserving artificially the vitality of 

 seeds, we shall find them offer a ready-explanation of 

 the success that attends some methods of packing, and 

 the constant failure of others. 



The great object of those who have devised means 

 of packing seeds for distant journeys has, in general, 

 been to exclude the air, and all other considerations 

 have been subordinate to this. Enclosure in bottles 

 hermetically sealed, in papers thickly coated with 

 wax, in tin boxes, and similar contrivances, have been 

 resorted to with this object in view : but no advan- 

 tage can be derived from excluding the air, and the 

 disadvantage is very great; for the effect of exclud- 

 ing the air is to include whatever free moisture seeds 

 may contain or be surrounded by ; this moisture is 

 sufficient, in high temperatures, either to deprive the 

 seed of its carbon of preservation, or to induce decay 

 of the tissue, especially of the seed-coats, which have 

 no vitality themselves, and in either case the embryo 

 perishes. 



Packing in charcoal has been recommended, it is 

 difficult to say why; and experience shows what 

 might have been anticipated, that it produces no other 

 effect than packing in earth or other dry non-con- 

 ducting material. 



Clayed sugar has been employed, and, as it is said, 

 occasionally with advantage ; but I have seen no in- 



