1152 Marvels of the Universe 
the midrib, with the result that the rolled part of the leaf falls to the ground—the precious eggs, 
of course, going with it. 
Now the marvellous thing about the birch leaf-roller is this: The grubs feed upon the decaying 
leaf-tissue, and eventually turn to pupe in the soil. Here they lie all through the winter, appearing 
as perfect weevils in the early summer. They 
at once creep up the birch stems, and the 
females, after pairing, immediately—without 
education or opportunity to profit by observa- 
tion—begin to cut and roll leaves after the 
manner of their ancestors. Whence comes 
their skill? How do they know the way in 
which the curved cuts should be made? We 
call this inborn knowledge “ instinct,’ but the 
word is really a cloak for our ignorance. For 
what instinct is, and how it originates, are 
unfathomed mysteries. 
Wise, CRUISE 
BY DR. ES J) SPIGRA,  ORSRS Mes: 
THE little Cricket that chirps on the hearth is 
an interesting insect, and seems always to have 
attracted attention, for its curious habit of 
hiding away in holes during the daytime and 
of coming out at night to chirp has even 
claimed the notice of the poet : 
“* On a lone winter’s evening, when the frost 
Has wrought a silence, from the stove there shrills 
The cricket's song.” 
Putting aside the general appearance of the 
insect itself, the points of interest to the worker 
with the microscope centre around the con- 
sideration of the chirping apparatus, the gizzard 
and the tongue. 
Commencing at the first, which is shown 
on page 1154, there cannot fail to be noticed 
a clear space something like a drum in the 
~ elytron, or wing-case. Looking nearer the 
~ body or thick end of this case, there will also 
Photo by} ; Ghent "TET. spatta, be seen a strongly-marked line—or nervure, as 
THE CRICKET’S FIDDLE-BOW. it is called—running across part of the wing- 
On looking at the Cricket’s wing-case a strong nervure will case. This can be recognized, even in the 
be seen running across part of it, marked by transverse notches. 5 ‘ : 5 
photograph, which is not very highly magnified, 
This bow when drawn across the drum of the opposite wing 
produces thesbighwpitched “chines by its having a series of notches or transverse 
file-marks upon it, running its entire length. It is shown much magnified on this page, and is 
usually called “the bow.” It is with this arrangement, used in conjunction with the wing-case of 
the other side, that the chirp is made. Messrs. Kirby and Spence thus describe it: “‘ The friction 
of these nervures of the upper or convex surface of the base of the left-hand wing-case—which is 
the undermost—against those of the lower or concave surface of the base of the right hand—which 
