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GALLS AND THEIR MAKERS IN ‘DEE’. 
BY PROF. JAMES W. H. TRAIL, AM, MB., F.LS. 
It seems to me best to restrict my remarks in this-paper to 
the galls and gall-makers that have been as yet observed in 
‘ Dee, though a notice of galls that would probably be found 
here if closely looked for, would prove of interest and value, 
and may possibly furnish material for a paper on a future 
occasion. The subject matter has been in. ‘great part published 
by me already in the ‘Scottish Naturalist, “vols. L. & IL, as I 
procured material for it, but the notes are so scattered that it 
seems likely to be of use to gather them up into systematic form, 
especially as they include almost all that is known on the 
occurrence of galls in the north of Scotland. I am happy to say 
that by the exertions of Messrs. Cameron and Binnie, our know- 
knowledge of the gall-makers about Glasgow has of late been 
- largely increased, while the eastern border counties have been 
rendered almost classic ground to the naturalist by Mr. Hardy. 
The same, however, cannot be said of Scotland north of the Tay, 
as very much yet remains to be done ere we can hope for any- 
thing like a thorough’ knowledge of galls and their makers in 
the north. 
Galls may be defined as outgrowths produced on some part 
of a plant by animal influence, for the purpose of yielding food 
and shelter either to the producer, or to the larva of the 
producer. They may be alterations of pre-existing parts of the 
plant, or they may be new growths, as will appear more fully 
farther on, 
One of the best classifications of galls as such, irrespective of 
their makers, is that proposed by Frauenfield ( Die Gallen ), and 
somewhat expanded by Schenck (Nassauischen Cynipiden und 
ihrer Gallen, &c., pp. 6-12). In it galls are divided into *hree 
great classes which may be rendered in English by the terms— 
1. Open galls—Those in which the central cavity of the gall 
is not entirely enclosed, an opening always remaining though 
sometimes very narrow. 
2. Closed galls, in which the central chamber is completely 
shut in. 
3. Lid-bearing galls, which open by means of a portion that 
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