212 ON PROP A GA TION B Y SEED. 



one-sixth part of a crop. After damping the seeds they were sprinkled 

 with quicklime, which, besides furnishing an alkaline, has a great 

 affinity for carbonic acid, which is necessary to be extracted from the 

 starch before it can be made soluble, and which produces heat by con- 

 centration of the oxygen and carbon when being extracted. The seed 

 was thoroughly damped and sprinkled with powder of lime for ten 

 or twelve days ; at the end of which time it had swelled off plump, 

 and had all the sweet smell of the sugar formed in healthy seed when 

 malted in this way : and, when deposited in the ground, it was not 

 long in pushing up its seed leaves, as healthy, upright, and dark green 

 in the colour, as the first year it was sown ; and the seedling plants 

 were strong and healthy. The reasons why I preferred lime were its 

 cheapness, and the affinity of quicklime for carbonic acid : as to its 

 alkaline properties, soda is much more powerful, but lime seemed to be 

 that which had produced most effect in other experiments on the same 

 subject. The seed must be carefully kept damp till sown, as the dry 

 powder is apt to corrode it ; and seeds should never have their dormant 

 powers brought into action without being sustained and carried for- 

 ward. Lime has likewise been applied to magnolias and other weak- 

 growing seeds difficult to start, and made them germinate sooner, and 

 make stronger plants than usual. 



The length of time during which seeds retain their vitality varies 

 exceedingly in different species ; and the difference in this respect, 

 even in the plants in common cultivation, as every seedsman knows, is 

 very considerable. It is remarkable that the seeds of annual plants not 

 only germinate in general sooner and with more certainty than those 

 of perennials, but also that they retain their power of germination 

 much longer. The greater part of the seeds of perennial plants and 

 trees, when well kept, preserve their germinating powers for a long 

 time ; while certain oily seeds, like those of dictamnus, magnolia, and 

 myristica, &c., decay soon after ripening. Melon-seeds have been 

 known to retain their vitality for nearly half a century, kidney-beans 

 for a century, and the seeds of the sensitive-plant upwards of sixty 

 years. 



The length of time that seeds will lie in the ground without grow- 

 ing, is not less remarkable than the difference in their retention of 

 vitality. Many seeds which, when sown in spring, come up soon after- 

 wards, will not come up the same year if sown in autumn. This is the 

 case with many common annuals, which when sown immediately after 

 ripening either do not come up at all that year, or come up sparingly 

 and sickly. On the other hand, the seeds of the greater portion of 

 biennial plants, if sown immediately after ripening, come up freely, 

 become strong plants before winter, and flower the following year. 

 This is also the case with a great number of annual plants, especially 

 those of California, which in their native country spring up before 

 winter, and are preserved through that season by a covering of snow. 

 The seeds of crataegus, mespilus, ilex, prunus, cerasus, and some others, 

 if sown immediately after being gathered, will in part come up the 

 following spring, but chiefly in the second spring, though some will not 



