Co lour -Changes in Leaves 393 



COLOUR-CHANGES IN LEAVES. 



The following list is supplementary to our article on 

 " Autumn Leaves " which appeared in last month's Gazette 

 The descriptions apply to some of the specimens which con- 

 stituted, during November, a special and temporary collection 

 in the Haslemere Museum. Many of the specimens have 

 been preserved, but fresh ones are always preferable, and 

 our list is intended for use with a future and more extended 

 collection. We hope also that it may be found useful in 

 other institutions where next autumn it may be thought 

 worth while to arrange similar exhibitions. There are few 

 more attractive subjects for careful observation during the 

 duller months of late autumn than those which concern the 

 very varied causes of the changes in colour shown by leaves. 



The observer should begin by noting the arrangement of 

 the colour changes. Are they alike on the two halves of the 

 leaf ? Do they begin at the top and borders ? Do they 

 assume any special pattern ? Is there, apart from mere 

 change in tint, any other peculiarity to be noted ? 



We have classified our material under several heads : — 



(1) Changes due to age. 



(2) Changes influenced by the presence of insects. 



(3) Changes influenced by the presence of fungal parasites. 



(4) Changes influenced by accidental damage. 



It must be understood that in most cases these influences 

 complicate each other, and that in all the effect of sunlight 

 is presupposed as the final cause of colour. 



Group I.— CHANGES INDUCED BY SENILITY (AND 

 SUNLIGHT). 

 Oak (Quevcus robur). 

 The colour-changes of senility always exhibit bilateral 

 symmetry. If, as is often seen in oak leaves, there is an 

 absence of symmetry, it may be concluded that the changes 

 were influenced by some external cause, even if such may not 

 be very evident. In the leaves here exhibited the symmetrical 

 markings indicate acroteric (senile) death, the non-symmetrical 



