AUTUMNAL FOLIAGE 



fected by light, and each gives a distinct spec- 

 trum. He suggests the collective name chromo- 

 phyll as a proper one for designating the pres- 

 ence of these various pigments. 



A study of the "Autumnal Changes in Maple 

 Leaves," by W. K. Martin and S. B. Thomas, 

 published in the Botanical Gazette for April, 

 1887, is instructive and illuminating. They 

 write as follows: "Chlorophyll manufactured 

 constantly under the influence of light is con- 

 stantly undergoing decomposition by the metab- 

 olism of the cell. Under ordinary conditions, 

 the manufacture of chlorophyll is sufficient to 

 cover up its decomposition and the leaf retains 

 its green color. Under changed conditions, 

 however, such as intense light or decreased vi- 

 tality, the decomposition of chlorophyll exceeds 

 its manufacture and xanthophyll, probably one 

 of the products of decomposition, appears. The 

 condition of intense sunlight gives us the occa- 

 sional summer yellowness, while to lowered vi- 

 tality must be attributed the failure of chloro- 

 phyll manufacture in the autumn. This lower 



136 



