The effects of LigJU on the Germination of Seeds. 397 



seed is charged. The seeds, when perfectly ripe, contain a 

 larger amount of carbon than any other part of the plant. 

 It is this carbon which preserves the seeds from decomposition 

 and decay ; but it also prevents them from germinating. 

 The only means of depriving the seeds of their carbon is by 

 supplying them with moisture. It absorbs the moisture, and 

 converts the carbon into carbonic acid by the oxygen thus 

 obtained. 



The formation and respiration of oxygen takes place most 

 freely in the dark, and hence darkness or shade is most 

 favorable to germination ; but no sooner is germination es- 

 tablished, or even begun, than light becomes necessary to 

 the farther development of the germ ; but the light is influ- 

 enced in a very epctraordinary manner by the medium through 

 which it passes, some being attractive in their character, 

 others repellant ; we will therefore consider the action of 

 the different media, or in other words, the action of the 

 different kinds of glass on plants under which they are 

 grown. Some beautiful and interesting experiments, per- 

 formed by Robert Hunt, on the effects of various colored 

 media on vegetation, may at this stage of our progress be 

 acceptable to your readers, and serve to elucidate the subject 

 perhaps better than any experiments of my own. 



Six boxes were so prepared that air was freely admitted to 

 the plants within them, without permitting the passage of any 

 light, except what passed through the colored glasses with 

 which they were covered. These glasses permitted the 

 permeation of light in the following order : — 



1. A Ruby Glass, (colored %oith oxyde of gold.) — This 

 glass permits the permeation of the ordinary red, and extreme 

 red rays only. 



2. A Brown Red Glass. — The ordinary ray and the orange 

 ray, produced by this medium, pass freely, above which the 

 spectrum is sharply cut off. 



3. Orange Glass. — The spectrum is shortened by the 

 cutting off of the violet indigo, and a considerable portion of 

 the blue rays. The green ray is nearly absorbed in the 

 yellow, which is considerably elongated. The whole of tlie 



