pO emerald 
eee c 
CONSTRICTION OF TWIGS BY THE BAG WoRM. 181 
the band of the bag worm where growth had stopped entirely. 3. Nor- 
mal wood of the red gum. 4. Wood of the red gum taken from a point 
immediately under the band of the bag worm where growth had stopped 
entirely. >< 400. 
Plate 26. — Photomicrographs showing the cross sections of wood 
taken at points immediately below the bands of the bagworm. The 
bands were situated at the top of both figures. Upper figure, from 
a maple constriction. Lower figure, from a red gum constriction. 
>< 50. 
DIAGRAMS. 
Diagram 1.— Showing the number of atmospheres pressure exerted 
by the bands of the bag worm, and the frequency with which the vari- 
ous pressures are exerted among 413 bands. The abscissae show the 
number of atmospheres pressure; the ordinates indicate the number of 
individual bands exerting any given pressure. 
Diagram 2.—a,. The relation between the varying widths of bands 
and the strength of the bands, expressed in terms of number of atmos- 
pheres presssure. The abscissae represent the number of atmospheres; 
the ordinates the number of individuals. —b. The relation between the 
varying diameters of twigs and the strength of the bands found en- 
circling them, expressed in terms of number of atmospheres pressure. 
The abscissae represent the number of atmospheres; the ordinates, the 
number of individuals. 
TEXT FIGURES. 
Figure 1. — Longitudinal section through an old swelling of the arbor 
vitae ( Thuja occidentalis), showing how the upper or outer portion grew 
in diameter, while the part below the band stopped growing entirely. 
(P. 189). 
Figures 2-4. — Longitudinal sections through constrictions of the soft 
maple, caused by the band of the bag worm. The figures show succes- 
sive stages of healing. Figures 2 and 3 show the top of the bag at the 
left of the constriction. (P. 160, 161). 
TEXT TABLES. 
Table I.—Showing the relation of the diameter of maple twigs to the 
width of the bands of the bag worm which were found upon them. 
(P. 176). 
Table II. — Showing a number of exceptionally strong bands, their 
dimensions and the trees they were found on. (P. 178). 
a 
