NATURAL SCIENCES OF PHILADELPHIA. 219 



often striped, and the dark colors would often be of various shades. 

 Besides this, European trees which bad no color in their own 

 country, when planted side by side with allied species here, still 

 preserved tiie same characteristics. Neitlier heat, nor light, nor 

 frost made the slightest change. The English oak beside tiie 

 closely allied American white oak retained its green color till 

 absolutely dried up b}' frosty winds. On the other hand, our 

 colored-leaved trees preserved their same colored characteristics 

 when growing in Europe under veiy dissimilar circumstances to 

 those at home. 



In spite of the visible action of the sun in the instances exhibited 

 and quoted, it was clear from the facts referred to, that solar or 

 chemical action could not be the sole cause of autumn colored 

 foliage. Though it seemed an incipient stage of decay, involving 

 chemical change, the coloring of the apple in the sunlight, or of 

 the autumn leaf, ceased if taken from its parent tree. It had to 

 remain on to the last, to get its full tints. Vital action of some 

 sort, therefore, must be taken into account by those who are 

 investigating the subject. 



The Committee to which it had been referred recommended the 

 following paper to be published : 



