46 
Rev. F. W. Hope on Succinic Insects. 
nets or opened a door communicating with an adjoining room 
having a similar aspect, when in the course of a few minutes 
three or four would enter, and singularly enough I found some 
difficulty in driving them out, as almost invariably they flew with 
violence against the upper panes, cautiously avoiding the net-work 
below, through which, had the free current of air been their guide, 
they might easily have escaped. Encouraged by this first attempt, 
1 prepared a net of very fine pack -thread, with enlarged meshes of 
1| inch to the square, and to my great satisfaction found that it 
answered the purpose as effectually as the smaller worked coloured 
worsted nets. So fine and comparatively invisible was the pack- 
thread net, that there was no apparent diminution of either light 
or the distant view, and for the remainder of the summer and autumn 
I was enabled to enjoy the fresh air with open windows without 
fear of the annoyance I had heretofore experienced. I should also 
add that, though wasps occasionally came through, the number was 
very much diminished. I attribute this valuable effect of net- 
work to the highly magnifying power of the organ of vision, added 
to the small focal length of the lens of the eye ; in consequence 
of which, the enlargement of each thread in their rapid flight pre- 
sents a succession of obstacles not discernible in the solid obstruc- 
tion of the panes of clear glass, against which they strike with the 
full force of accelerated motion when endeavouring to avoid the 
attempts of those who would catch them. 
X. Observations on Succinic Insects. By the Rev. F. W. 
Hope, M. A., F. R. S., fyc. 
PART THE SECOND. 
GUMS AND RESINS. 
[Read April 7, 1834.] 
In commerce the term gum is indiscriminately applied to resins as 
well as to gums, and we not unfrequently meet with the following 
improper appellations, Gum Copal, Gum Anime, both of which are 
resins. It is true, indeed, that these substances have some pro- 
perties in common which are not at first sight readily perceived ; 
