hy Lindlei/s Theory of Horticulture. 437 



it still further increased the growth ; also that in tannin they would 

 not grow at all. Mr, R. Hunt (quoted from the Philosophical 

 Magazine, in the Gardener's Magaziiie for June) exposed cress 

 seeds to blue, green, red, and yellow rays of light ; the red and 

 yellow rays, which are the colours said to be produced by bodies 

 abounding in acids, destroyed the seeds altogether ; while in the 

 blue and green rays, in which alkalies are allowed to predominate, 

 the seeds grew well, and best in the blue. All these experiments 

 seem to point to alkalies as beneficial in germination. Oxygen 

 is necessary to reduce the starch, by extracting its carbon in the 

 form of carbonic acid. Dr. Lindley seems to think this oxygen 

 is principally obtained from the decomposition of the water. Mr. 

 Ellis, and the author of Botany [Library of Use/id Knowledge), 

 seem to think it is principally derived from the air, perhaps it 

 may be derived from both sources ; the oxygen of the air being 

 only mechanically, not chemically, combined with the nitrogen, 

 should be easily separated. That air is necessary in germination 

 seems corroborated by the fact, that seeds will preserve for an 

 almost indefinite period of time, if buried deep in the earth, be- 

 yond the action of the air, though subject to moisture and heat ; 

 like toads enclosed in stone, if the seclusion be complete, the seed 

 may live for centuries. Light is prejudicial to germination, as it 

 causes the emission of oxygen, and helps to keep the carbon fixed; 

 and starch, having more carbon than mucilage, must part with it 

 before the food becomes soluble. The great endeavour, in the 

 germination of seeds, should be to get as much of the food as 

 possible made soluble ; the strength of the growth of the young 

 plant depends upon the quantity made available by solution, and 

 not ou the absolute quantity present. In seeds containing a great 

 quantity of highly concentrated food, germination proceeds very 

 slowly. We have had seeds of Gleditschm triacanthos to lie in 

 the ground for years before germinating; and these and other 

 acacias are said by Cobbett and others to be the better of being 

 exposed to the steam of boiling water for some time, to help in 

 the solution of their food ; but this should be done with caution. 

 Onions, spinage, and some other seeds, may be made to sprout 

 their radicle in the course of twenty or thirty minutes, if ex- 

 posed to the steam of boiling water, but this over-excitement 

 weakens them, and is not beneficial, unless to test the quality of 

 a sample. The moist heat of a dung hot-bed is safest, and few 

 seeds will be found to resist this, if sound and fresh, and come 

 to their ordinary time of springing, which differs much in seeds, 

 and for which there is no general rule. Dry farinaceous berries, 

 with hard stony kernels, lie longest, as the holly, which will 

 sometimes lie three or four years in the ground, and thorns two 

 or three years ; the cherry, which has a hard kernel and pulpy 

 fruit, comes generally the next or first year, if sown in autumn ; 



