Wie eS Oe ee, ee 4 ge 
180 MISSOURI BOTANICAL GARDEN. 
nung zur Bildung der Jahrringe und zur Ablenkung der 
Markstrahlen. (Sitzungsber. der Kgl. Preuss. Akad. d. 
Wiss. 51: 1093. 1882). 
6. Krabbe, G. Uber das Wachstum des Verdickungs- 
ringes und der jungen Holzzellen in seiner Abhingigkeit 
von Druckwirkungen. (Sitzungsber. d. K. Preuss. Akad. 
d. Wiss. 53:57, 69, 1884.— Also Separat aus Abh. d. K. 
Preuss. Akad. d. Wiss. 1884). 
7. Kiister, E. Uber Stammverwachsungen. (Prings. 
Jahrb. f. Wiss. Bot. 83:487. 1899). 
8. Sachs, J. Lehrbuch der Botanik. 409. 1868. 
9. de Vries, H. Del’influence de la pression du liber 
sur la structure des couches ligneuses annuelles. (Extrait 
des Archives Néerlandaises. 1876). 
EXPLANATION OF PLATES. 
Plate 20. — Constrictions caused by the bands of the common bag worm 
(Thyridopteryx ephemeraeformis Haworth) on branches of arbor vitae 
(Thuja occidentalis). Natural size. 
The two upper figures are living branches. The lowest one shows a 
branch kiiled by the band of the bag worm. 
Plate 21.— The bag worm on living one-year-old branches, as it appears 
a month after the attachment of the bags, usually about the end of 
September. The upper figure shows it on a sycamore branch, the lower 
on a branch of the ash-leaved maple. Natural size. 
Plate 22.— Constrictions caused by the bag worm on maple twigs of 
various ages. 1. Twig two years old showing early stage of constric- 
tion. 2. Twig 2 years old, showing beginning of union of two lips. 
3. Twig 3 years old with healing almost complete. 4. Branch ten years 
old, healing complete, and top of bag partially overgrown by the wood. 
Natural size. 
Plate 23. — Constrictions caused by the bag worm in various hardwood 
trees. 1. On willow. 2. On locust. 8.On sycamore. 4. On red gum, 
6. On sassafras. 6. On poplar. 7. On white oak. 8. Onapple. 4. 
Plate 24.— Constrictions caused by the bag worm on various conifer- 
ous trees. 1. On Pinus virginiana. 2. On Thuja occidentalis. 3. On 
bald cypress. 4. On larch. 5. On Deodar cedar. 6. On hemlock. 7, 
8. On Deodar cedar. X 4. 
Plate 25.— Cross sections showing structure of normal wood, and 
wood from the bag worm constrictions. 1. Normal wood of the soft 
maple. 2. Wood of the soft maple taken froma point immediately under 
, 
