CURRANT GALLS — SPANGLE GALLS. 511 



That this supposition may be correct is evident from the fact 

 that the same insect which forms the oak apples does also deposit 

 its eggs in the root of the same tree, causing large excrescences to 

 spring therefrom, each excrescence being filled with, insects. I 

 have often obtained these root-galls, several of which are now be- 

 fore me, some having been cut open, in order to show the numer- 

 ous cells with which they are filled, and others left untouched, in 

 order to exhibit the form of the exterior. Being nourished by 

 the juices of the root, they partake of the sombre hues which 

 characterize the part of the tree from which they spring, and do 

 not display any of the colors which are seen on the oak apples 

 which spring from the twigs. 



There are, however, distinct species of gall insects which pierce 

 the roots of the oak-tree. One of them is termed Cynips aptera, 

 and makes a pear-shaped gall about one third of an inch in diame- 

 ter. Each gall contains a single insect, and a number of the galls 

 are often found attached by their narrow end to the root-twigs of 

 the tree, something like a bunch of nuts on a branch. There is 

 another insect which is termed Cynips quercus-raclicis, which forms 

 a many-chambered gall of enormous size, containing a small army 

 of insects. Mr. "Westcott mentions that one of these galls in his 

 possession was five inches long, one inch and a quarter wide, and 

 produced eleven hundred insects, so that the entire number was 

 probably fourteen or fifteen hundred. 



No one who is accustomed to notice the objects which immedi- 

 ately surround him can have failed to observe the curious little 

 galls which stud the leaves of several trees, and which are appro- 

 priately called Spangle Galls, because they are as circular, and 

 nearly as flat, as metallic spangles. 



These objects had been observed for many years, but no one 

 knew precisely whether their growth was due to animal or vege- 

 table agency. That their substance was vegetable was a fact 

 easily settled, but some botanists thought that they were merely 

 a kind of fungus or lichen, while others supposed that they were 

 the work of some parasitic insect. 



When closely examined, these " spangles" are seen to be disks, 

 very nearly, but not quite flat, fastened to the leaf by a very small 

 and short central foot-stalk. Eeaumur set at rest the question of 

 their origin by discovering beneath each of them the larva of 

 some minute insect, but he could not ascertain the insect into 



