OF SEED-PACKING. 179 



shire, after tKe surface has been drained and the soil 

 ploughed, large crops of white and black mustard 

 invariably appear. Miller mentions a case of Plan- 

 tago Psyllium having sprung from the soil of an 

 ancient ditch which was emptied at Chelsea, although 

 the plant had never been seen there in the memory 

 of man. De CandoUe says that M. Gerardin succeed- 

 ed in raising Kidneybeans from seed at least a hun- 

 dred years old, taken out of the herbarium of Tourne- 

 fort ; and I have myself raised Easpberry plants from 

 seeds found in an ancient cof&n, in a barrow in Dor- 

 setshire, which seeds, from the coins and other relics 

 met with near them, may be estimated to have been 

 sixteen or seventeen hundred years old. 



In these cases, the only circumstances that we can 

 conceive to have operated must have been such a de- 

 gree of dryness as prevented the decomposition of the 

 seed on the one hand, and the excitement of its germi- 

 nating powers on the other, a moderately low tempe- 

 rature, and in some of them the exclusion of air ; for 

 moisture, heat, and communication with the air, are 

 ■necessary to enable seeds to grow (14). The tendency 

 of moisture exposed to the air, and in contact with 

 inert vegetable matter, such as a torpid seed, is by de- 

 grees to produce decay, which rapidly spreads to the 

 neighbouring parts. But, if the vitality of a seed is 

 excited by a fitting temperature, the moisture with 

 which it is in contact is then decomposed, the oxygen 

 so obtained combines with the carbon of the seed, and 

 forms carbonic acid, which flies off, and by degrees re- 

 duces the amount of carbon lodged in the tissue of the 



