Stone: Autumnal Coloration of Leaves 201 



of extreme moisture. No two seasons seem to give rise to the 

 same intensity of coloration. During seasons when there are no 

 extreme differences in temperature intense scarlet colorations are 

 lacking ; on the other hand marked difference in temperature gives 

 rise to an intense coloration of a great variety. The duration of 

 coloration is also equally variable. Some seasons the color has a 

 long period of duration while in others it is brief. The past season 

 was one in which the transformation from green to yellow, scarlet 

 and brown, and subsequent fall of the leaf was brief in the Con- 

 necticut Valley, a feature which, according to the writer, was 

 hastened by excessive cloudy weather and rainfall during the 

 period of transformation. The work of borers is also an impor- 

 tant factor in the premature coloration of white and sugar maple 

 trees. Borers however are generally confined to one or more 

 limbs and the premature coloration of these, while the rest of the 

 tree may still be green, is of common occurrence and they can 

 be readily picked out at a glance. 



In fact any abnormal condition of the limbs or tree whether 

 brought about .by insects or fungus intrusion or from purely 

 physiological disorders are capable of giving rise to premature 

 coloration in the leaves, which to the pathologist possess interest. #. 



