GALLS AND PARASITES. 285 



France, where the liquid which they contain is called 

 eau de TOrme, and is recommended as a wash for 

 wounds, contusions, and sore eyes. In the autumn, 

 when the galls become dry, the residue has the form 

 of a yellow balsam, when it is said to be employed 

 for diseases of the chest. 



ELM-ROOT GALLS. Other galls are found upon the 

 roots of the elm, varying in size from that of a pea 

 to a walnut, uniting together in irregular masses, and 

 having a rough, reticulated exterior, so as to resemble 

 truffles. These inclose insects of the Cynips l kind, 

 but both sexes are without wings. They are not com- 

 mon in Britain. 



SPRUCE-CONE GALLS. The young twigs of spruce 

 are liable to assume the appearance of small fir- 

 cones, with part of a branch springing from the top, 

 but they are in reality a peculiar form of gall, caused 

 by aphides, 2 and inclosing quite a colony. These 

 galls are about an inch in length, and half as much in 

 diameter. From their resemblance to small cones these 

 curious malformations are liable to be overlooked. 



POPLAR-LEAF GALL. It is a very common circum- 

 stance to find the petioles, or leaf-stalks of the poplar, 

 especially of the common black poplar, swollen in a 

 gouty manner into an oval cr irregular-shaped gall, 

 which occasionally occurs on the midrib of the leaf 

 itself. This gall is not much larger than a pea, but 

 it usually contains a large number of aphides 3 with- 

 out wings, together with four or five winged ones. 

 As in the case of the elm galls, these are hollow ; 

 indeed, the structure of the galls, or cases, which are 

 produced by aphides, is quite different from that 

 1 Cynics aptera. * Adetges abietis. 3 Eriosoma bursari-a. 



