Autumn Leaves 



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will be much like those of old age. It will be a case of 

 premature ageing. The possible injuries to the leaf itself 

 may be very various. There may be a burrowing grub, and 

 the mined portion of the leaf will die and change colour. 

 It may be a huge blotch, as in the common dock, or an 

 elegant gyration, as in the bramble and many others. It 

 is never, except by mere chance, symmetrical, and seldom 

 involves the mid-rib. 



The growth of the smaller fungals on leaves often pro- 

 duces beautiful changes in their colour. The patches on 

 bramble leaves, often becoming in late autumn of a blood red 

 colour, are caused by the growth of plots of the Phvagmidmm 

 bulbosum on the under surface. These changes in colour may 

 be arranged with symmetry if the fungal chance to have been 

 so planted, but more usually they are quite irregular. A good 

 example of another class of fungal-caused changes is very 

 frequent in the patches like splashes of tar which occur on 

 sycamore leaves. In this instance, however, the fungal itself 

 produces the patch and the colour, rather than causes the leaf 

 to do so. There are a great variety of fungals which grow 

 on leaves and cause colour-changes. The growth of galls on 

 leaves may cause colour-changes in two different directions. 

 If on the under surface of the leaf, as in the commonest of 

 all instances, the cheese-cake gall of the oak leaf, they usually 

 cause the part to die, and a patch of brown is seen on the 

 surface. If very abundant they may kill the whole leaf, but 

 not until the gall has had time to attain its own growth. If 

 the galls grow from the upper surface of the leaf, instead of 

 killing the part, they appear to maintain its nutrition by 

 continuing to attract sap when the rest of the leaf has ceased, 

 owing to age, to be able to do so. Most interesting illustra- 

 tions of this curious fact may often be picked up under beech 

 trees. Certain of the fallen leaves will be noticed to have 

 streaks of bright green on them, and on careful inspection 

 there will be found on these one or more of the galls of the 

 Hermomyia peligera. The galls themselves keep green, and the 

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