COLOURS OF GALLS. 
3 Ji 
Botanists and physiologists will see that this idea is quite 
groundless, but to the uninstructed and popular mind it has a 
sort of plausibility that often commands assent. But when we 
come to the oak-tree the case is at once altered, and some other 
cause must be found for the lovely colours of its galls. The 
cherry-galls are as brightly coloured as any apple, and the soft 
hues of the oak-apple are nearly as beautiful though not so 
brilliant. Yet the oak possesses no such store-house of colour 
as is popularly attributed to the rose. Its leaves are simple 
green, and its flowerets are so colourless as scarcely to be dis- 
tinguished by the unassisted eye. 
Whence then are derived these beautiful colours ? Some hasty 
observers, who have neglected the first rule of logic, and drawn 
an universal conclusion from particular premises, have said that 
the colours of the gall are derived from the insect; adducing, 
as a proof of their assertion, the brilliant colours which equally 
deck the rose-bedeguar and the Cynips rosa from which it sprang. 
But if they had only followed the example of careful naturalists, 
who, like Dr. Hammerschmidt, have examined and drawn be- 
tween two and three hundred species of galls, so hasty a gene- 
ralisation would never have been made. The cherry or leaf-gall 
of the oak is every whit as gorgeously coloured as the bedeguar 
of the rose, while the insect that made it is quite black. It is 
true that the diaphanous wings glitter as if they were made of 
polished gems; but this appearance is due, not to the wings 
themselves, but to the myriad hairs with which they are regu- 
larly studded, each hair acting as a miniature prism by which 
the light is refracted and broken into the resplendent hues of 
the rainbow. 
Many other trees besides the oak are chosen by certain species 
of gall-fly, and even the herbs and flowers do not escape the 
ravages of these remarkable insects. The white poppy, from 
which is obtained the opium of commerce, is attacked by a 
species of gall-fly, which lays its eggs in the large head, or pod, 
and sometimes does much damage to the plant, the delicate 
divisions between the seed-vessels being rendered quite hard 
