3o8 STRANGE DWELLINGS. 



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 discs, 

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

 small and short central footstalk. Reaumur 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 which the larva would in process of time be deve- 

 loped. The task of rearing the perfect insect from the gall is 

 exceedingly difficult, the minuteness of the species and the 

 peculiar manner in which the development takes place, being 

 two obstacles which require a vast expenditure of care and 

 patience before they can be overcome. 



Supposing a branch containing a number of infested leaves 

 to be placed in water and surrounded with gauze, it will die in 

 a week or two, and yet there will be no sign of an insect. If 

 the branch be kept until the winter has fully set in, the desired 

 insects will still be absent, and the experimenter will probably 

 think that his trouble has been thrown away. The real fact is, 

 that the little insects are not developed until' the spring of the 

 following year, and that they pass through their stages of the 

 pupal and perfect forms after the leaves have fallen, and while 

 they are still lying on the ground. 



Mr. F. Smith, who has given so much time and research to 

 the history of the hymenoptera, has discovered the insect that 

 inhabited the galls to be Cynips longipennis, and has remarked 

 that the perfect insects do not make their appearance until the 

 month of March. I have had many specimens of this tiiw and 

 beautiful insect. 



