72 Vezu- Trees of Great Britain and Ireland 



duction of galls was due to a minute quantity of 

 poison introduced by the gall insect, but this view 

 is no longer tenable. Dr. Adler^ has shown con- 

 clusively that there is no foundation whatever for 

 this supposition, and Beyerinck has proved that the 

 fluid ejected by the gall-fly is without taste or smell, 

 and absolutely unirritating if injected under the 

 skin. It is probably nothing more than ' a very 

 mild antiseptic' dressing applied to the wound made 

 in the plant. Both these authors show that it is 

 not in the gall-mother but in the larva that we 

 must seek for the cause of gall-growth. These 

 galls are, in some districts, exceedingly abundant ; 

 notably in Gloucestershire and Somersetshire, in 

 Kent and in Windsor Park. Farther north they 

 are much less frequent ; while in Scotland they are 

 unknown.- Not only is the opinion held by Loudon 

 and Selby, that the yew is seldom attacked by 

 insects, untrue, but there are instances which show 

 that no tree suffers so disastrously from their attack. 

 AtTintern, on the Wyndcliffe, in May 1889, I found 

 most of the trees largely affected by galls. In some 

 instances every twig had its terminal rosette, and it 

 was apparent that this invariably led to the death of 

 the shoot, as the tree was covered with the dead twigs 

 of several years and was almost destitute of foliage ; 



^ Alternating Generations : A Study oj Galls, etc. Translated by C. R. 

 Straton, F.R.C.S. 

 ^ And. Prof. Trail. 



