396 The effects of Light on the Germination of Seeds. 



Art. III. The effects of Light on the Germination of Seeds, 

 Sj'c., when passed through media of various colors. By 

 R. B. L. 



This subtile agent, which exercises such a wonderful in- 

 fluence on animate and inanimate matter, plays a very impor- 

 tant part in the germination of seeds, and propagation of 

 plants ; but more interesting still is this subject when the 

 distinct effects of the separated rays are made the subject of 

 experiment and investigation, showing how beneficial this 

 branch of physiological science is to gardeners and horti- 

 culturists, especially those engaged in the propagation of 

 delicate and tender plants. 



It is pretty generally known by gardeners that the general 

 conditions necessary to the germination of seeds are mois- 

 ture, heat, and the presence of oxygen gas. The neces- 

 sity of LIGHT has not been recognized, though every gardener 

 knows that a certain amount of atmospheric air is requisite 

 immediately on the germination of the seed, otherwise the 

 embryo will become enfeebled, and very soon decay. So also 

 at this stage of the embryotic process is a certain amount of 

 LIGHT necessary, if the germinated seed is to be maintained 

 in a healthy state ; the vital principle at this period of its 

 growth is acted upon by separate influences contained in the 

 different rays which are in action upon the plant. These 

 influences, therefore, and the effects resulting therefrom, 

 constitute the subject of the present article. 



The amount of these agents necessary for the full and free 

 development of seeds, must be exceedingly variable in the 

 vegetable kingdom. Some seeds germinate freely at the 

 freezing point, (32°,) in an atmosphere comparatively arid ; 

 while others, and perhaps the majority of seeds, require a 

 high humid temperature for their perfect development ; but 

 every degree between the two extremes is requisite for the 

 proper development of some individual species, and the 

 requisite degree of heat and moisture thus required will 

 always depend on the amount of carbon with which the 



