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The Museum Gazette 



part of them which is of vegetable production is evidently 

 still living. Much depends upon whether the gall itself is 

 living or dead. In the case of the oak, the egg within is, of 

 course, alive, but the vegetable structure which encloses it 

 is dead. It is a necessary consequence that it should die, if 

 it kills the part of the leaf on which it grows, and from which 

 it derives its own nutriment. The lesson in biology which 

 we here learn is one of great interest. The changes in colour 

 caused by galls like those from fungals are never, except by 

 accident, alike on both halves of the leaf (bilateral symmetry). 

 Although living and still growing galls appear to be the most 

 efficient agents in maintaining the green chlorophyll in dying 

 leaves, they are by means the only ones. Many kinds of 

 injury may do it. The burrows of leaf-miners are often seen 

 surrounded by green. The retention of colour probably 

 follows on changes in structure which have been induced. 

 Insects which prick leaves in order to suck the sap may 

 cause colour-changes. Those of the aphis or plant-lice tribe 

 are the most common offenders. Oak leaves may be gathered 

 speckled all over with pin-head spots of white, and on looking 

 under them aphides will be found in all stages of development. 



We have by no means said all that might be said with 

 profit as to the changes in colour of autumn leaves. Enough 

 has, however, perhaps been said to enable any one who has 

 made a collection of such leaves to group them in connection 

 with the causes which have been influential, and to observe 

 their differing features with intelligence. 



We shall give next month a descriptive list of the speci- 

 mens which have been on exhibition at the Haslemere 

 Museum recently. We purpose to give also a list of the 

 drawings which we possess in illustration of the subject. 

 Most of these have been beautifully drawn in water colours 

 by a skilful artist. If ever the subscription list to our 

 Gazette should enable us to do it without too heavy loss, 

 we shall be glad to present our readers with, a selection from 

 them. 



