ji; \\'iw>nsin Academy of Sciences, Arts, and Letters. 



i iv. trunks had a greater radius on the side toward which they 

 *l;mt mid also have "red- wood" present on the side with the 

 longest radius. In one instance a tree on the west edge of a for- 

 est and therefore having most of its branches on the west side 

 was found to have a longer radius as well as abundant "red- 

 wood" on the east side. In another case trees along the western 

 .-d;e of a forest had the typical excessive growth and "red- 

 wood" on the east side of the trunks up to the age of about 80 

 to 90 years, after which the new rings showed a lesser excentric- 

 ity and a smaller amount of "red-wood." The change seemed 

 to have resulted from the presence of a new planting on the west 

 side which had attained some size by that time. Hartig con- 

 cluded that the mechanical or swaying effects of wind not only 

 causes excentric radial growth but also induces the formation of 

 "red -wood" on the side of trunks subjected to longitudinal com- 

 pression. An instance is also cited in which the leeward side of 

 a tree-trunk is excessively thickened from the base up but which 

 was devoid of "red-wood" near the ground although it was abun- 

 dant farther up. A case is described where the distal part of a 

 young spruce stem had been bent into a complete turn and had 

 grown in that position during 27 years. Sections cut at various 

 points of the curve showed the occurrence of the greatest radial 

 growth and of "red- wood" on the sides where gravity and lon- 

 gitudinal compression resulting from the top-weight and wind 

 action would require it. The excentricity of large spruce 

 branches and the accompanying "red-wood" was found to ex- 

 tend only about four meters out from trunks. 



According to Hartig "red-wood" has comparatively large 

 intercellular spaces and the cells seem not to be very firmly at- 

 tached since they frequently fell apart in sections. The tra- 

 cheids are said to have especially thick walls the innermost thick- 

 ening layers of which are arranged spirally. 



In a more recent summary of his investigations of wood Har 

 tig 45 claims to have proved the relative influence of gravity and 

 longitudinal compression in inducing the formation of "red- 

 wood." Spruce trees planted in large tubs were suspended in 

 an inverted position in a greenhouse and the distal part of the 

 stems were bent upward and allowed to grow during one sea- 



5 Hartig, R. Holzuntersuchungen. Altes und Neues. Berlin. 1901. 

 pp. 99. 



