Grossenbacher — Radial Growth in Trees. 25 



Cieslar 43 performed an experiment which suggests the above 

 cited observations by Nordlinger in that he bent over the tops of 

 four eight-year-old spruce trees and tied them in a horizontal po- 

 sition in early summer, one was bent toward each of the four 

 cardinal points. All ascending branches were also fastened 

 horizontally. The trees were cut during the second winter fol- 

 lowing the beginning of the experiment and the radial growth 

 was found to have become greater on the upright nasal portion 

 of the stems on the side of the bent-over tops. The excentricity 

 increased from near the ground up to a maximum beyond the 

 middle point of the turn where the stem was horizontal. Start- 

 ing in the outer ring some distance above the inception of ex- 

 centric growth and extending even into the outer part of the 

 third ring, the wood on the side having the longer radius had a 

 reddish color, which also became darker upward in proportion to 

 the increase in the radius. That is, the rings produced the year 

 before the trees were bent were also affected by the bending. It 

 is also shown that the spring-growth of the affected rings is not 

 discolored in the lower part of the stained region. 



Such "red-wood" as described above is very commonly present 

 in the under half at the base of pine and spruce branches. The 

 physical properties of "red wood" have been studied in some de- 

 tail and its histological characteristics have also received some 

 attention. Although it seems not to occur in stem structure de- 

 void of exeentric growth, excentricity is not always accompanied 

 by ' ' red wood. ' ' The fact brought out in the above cited paper 

 by Cieslar that the summer wood may be affected while the 

 spring wood of the same ring is normal is especially noteworthy 

 because it shows that the factors producing "red-wood" are not 

 effective throughout the year. 



Hartig 44 made an investigation of the occurrence and distri- 

 bution of "red-wood" in spruce and found that it is always pres- 

 ent on trees which have exeentric trunks and are located in iso- 

 lated places or in thin and interrupted forest stands. Since 

 "red-wood" occurs in portions of trees which appear to be sub- 

 ject to the greatest strains, Hartig thinks it arises in response to 

 the mechanical requirements of stems. He found that inclined 



43 Cieslar, A. Das Rothholz der Fichte. Centbl. Gesam. Forstwesen. 

 22:149-65. 1896. 



"Hartig, R. Das Rothholz der Fiehte. Forst. Naturw. Zeit. 5:96-109; 

 157-69. 1896. 



