142 COLOR. 



shape, rather approaching the sphere, but somewhat angular, 

 and consist of a semi fluid, gelatinous mass, not enclosed in a 

 sac. It is affirmed by some to contain iron and manganese, to 

 which the varieties of color are owing, produced by the acces- 

 sion of these different substances, as it is well known that al- 

 most every hue may be produced by these two metals. But 

 the quantity of chromule which exists in plants is exceedingly 

 small ; Berzelius estimated the quantity in the leaves of a large 

 tree not to exceed three and a half ounces. 



200. To enable plants to deposite chromule, light in most 

 cases, is absolutely necessary. This is abundantly shown by 

 the fact, that plants growing in the dark become blanched; 

 not that the chromule already deposited becomes less, but that it 

 issurrounded by the deposition of substances containing no chro- 

 mule, and of course becomes less observable. There are exam- 

 ples however, of plants, growing in deep mines, having never 

 enjoyed the light of day, which, nevertheless are green. 



201. Green is considered the natural color of vegetation, 

 and when it is not of this hue in the language of Botany, it is 

 said to be colored. 



202. The change of color produced on chromule, has been 

 referred to different causes. The two most deserving of no- 

 tice, are the one of Schubler, and Funck of Tubingen, and 

 the other of Macquart. 



Both theories consider green as the original color, but 

 the means by which the variations are produced, are account- 

 ed for on very different principles by the supporters of the 

 two theories. Schubler and Funck maintain that all varia- 

 tions from green are produced by acid, or alkaline secretions. 

 The green chromule acted on by these substances assumes every 

 variety of hue. The hues assumed by the flowers, are deter- 

 mined by the d'fferent agents by which they are produced, 

 with the exception of red ; this is common to both. Those 

 produced by the action of the alkaline secretions, from green, 

 are 



Greenish blue, Violet. blue, Violet-red, 



Blue, Violet, Red. 



This is called the Blue, Cyanic or Disoxydized series, 

 and any variation of color from one of these hues, will always 

 be by passing into some o(her of the same series. 

 Those colors produced by the acid secretions are 



Yellovv-green, Orange-yellow, Orange-red, * 

 Yellow, Orange, Red. 



These constitute what is called the yellow, xanthic or oxy- 

 dized series, 



