44 BRECK'S NEW BOOK OF FLOWERS. 



principally upon the degree of oxygenation. In leaves 

 fully developed the chromule is green ; it gains a tendency 

 to yellow or red when it is more oxidized, as one per- 

 ceives by the changes of the color of leaves in autumn, by 

 the effect of acids ; and it appears to verge to blue when 

 it is less oxidized. We know that the flower of the Hy- 

 drangea becomes blue in a soil sufficiently impregnated 

 with iron." 



" The nature of this work does not admit of a very ex- 

 tensive discussion of this subject in its pages, but it may 

 be well to show that plants do contain metallic oxides." 



" Dr. Sprengel, in a German publication called Der Land 

 und Hauswirth, or the Agricultural and Domestic Econo- 

 mist, states that in almost all plants analysis discovers more 

 or less iron, and as the atmosphere does not contain any 

 sensible quantity, it must be admitted that it is derived 

 from the soil." 



" In Sir Humphrey Davy's Agricultural Chemistry, it Is 

 stated that the only metallic oxides found in plants are 

 those of iron and manganese, but there is little doubt that 

 copper exists in the Rose, as may be verified by leaving a 

 clean linen rag in rose water or in the water in which 

 rose leaves have been steeped ; after some days it will 

 turn green, and copper may be detected, even when the 

 rose water has been distilled in glass or new tin vessels. 

 I remember to have seen a scientific account in some 

 French publication, of gold being extracted, from the sage 

 plant, although in very small quantities. Iron and manga- 

 nese would however be sufficient to produce almost every 

 variety of color known." 



" Immediately after the flower withers, a change in the 

 juices of most plants takes place, by which change the 

 fruit or seed is matured ; this is very perceptible in the 

 eatable fruits, and proceeds until acidity becomes obvious 

 to the taste; after this saccharine juice is formed now if 



