AUTUMN 
     
     COLOUR 
     
    
   
   
    
     Cur understanding of why leaves change colours in fall is far from 
     
     conplete. Two types of factors are thought to be involved: 1. changes 
     
     within the leaf, particularly those concerning development of pigments; 
     
    

    
     2. changes in conditions outside the leaf (e.g.- weather). Autumn colours 
     
     are also associated with the waning vitality of the leaf. As summer and the 
     
     growing season draw to a close, a special layer of cells is formed at the 
     
     base of the leaf which prevents water and other materials fron entering or 
     
     leaving the leaf. This slows down processes occurring in the leaf and 
     
     interferes with the production of chlorophyll, the green pigment which most 
     
     plants use to make food. After existing supplies of chlorophyll are used 
     
     up, the leaf loses its green colour. This allows any other pigments present 
     
     in the leaf to show up, and also permits production of new colouring matters 
     
     not previously present in the leaf. _ 
     
    

    
     In an ordinary leaf there are always yellow pigments associated with 
     
     the green chlorophyll. Thus, unless there are other pigments present to 
     
     mask it, a leaf will turn yellow after its green pigment has disappeared. 
     
    

    
     The red colours we see are caused by pigments which form after the 
     
     leaf begins to decline. The formation of red pigments apparently requires 
     
     plenty of light, and it may be that the disappearance of green permits enough 
     
     extra light to enter the leaf to permit red pigments to form. Perhaps it is 
     
     partly for this reason that the most brilliant leaf colours are often found 
     
     when the autumn season is bright and sunny rather than dull and cloudy. 
     
    

    
     Leaves which develop the greatest intensity of red, like the maples, 
     
     are often rich in sugar. Red colour is usually richest in seasons when 
     
     there is an abrupt change Eran high summer temperatures to low autumn 
     
     temperatures. Perhaps under such conditions the movement of Sugars and 
     
     other materials out of the leaf and into the rest of the tree for winter 
     
     storage is retarded. The presence of sugar in the leaf seems to be a 
     
     starting requirement in the fonmation of red pigment. 
     
    

    
     Although frost may play a part in autumn colouration, it is not 
     
     essential_as many leaves are observed to turn red or yellow before the first 
     
     frost occurs. As the season advances and the nights become colder, colours 
     
     gradually fade due to the breakdown of pigments and other compounds within 
     
     the leaf. As the products of these decunposition processes accumulate, the 
     
     leaf acquires a brown colour and eventually falls to the ground. 
     
    

    
     ‘3.- 
     
    
   
   
    
     THANKSGIVING DAY WALK. Despite the ladk of cooperation from the weatherman, 
     
     sane lO hardy sculs braved rain and high winds to enjoy a walk arcund the pond 
     
     at Moore's Bird Sanctuary on the 8th of October. The presence of some avid 
     
     naturalists from Montague raised the spirits of the group who found the new 
     
     board-walks most helpful in getting over some of the wet spots on the trail. 
     
     The inclement weather prevented bird watching; however, the front pond was host 
     
     to several hundred Canada geese, and both black and mallard ducks. The woods 
     
     were full of mushrooms, many of which Art Reddin was able to identify. On the 
     
     return trip to Charlottetown, a quantity of shaggy mane (Coprinus comatus) 
     
     were collected fitnxthe Vernon River area and which according to one mushroom 
     
     fancier, provided that extra touch to Thanksgiving Dinner that evening.