BOTANY AND ZOOLOGY 



Studies of eccentric growth in trees have 

 Eccentric shown that in general the increased wood 



Growth formation takes place on the concave side 



of Ash in conifers and on the convex side in hard- 



woods. The phenomenon is to be noted in 

 the case of horizontal branches, roots, isolated trees exposed to 

 wind, trees growing on a slope or on the border of a dense wood, 

 and in case of branches or trees accidentally or experimentally- 

 kept in a bent position. 



The general explanation offered is that the eccentric growth is 

 a restdt of the longitudinal forces of tension and compression set 

 up in the convex and concave sides respectively by the bending. 

 In the case of conifers the cells of the increased growth are abnor- 

 mally lignified, and the wood in consequence is more adapted to 

 withstand compression than tension; whereas in the hardwoods, 

 these cells are found to be very imperfectly lignified and corre- 

 spondingly more elastic and able to withstand tension. This leads 

 to Metzger's explanation of the appearance of the greater amount of 

 wood on the concave side in conifers and convex side in hardwoods ; 

 taking the character of the cells into account these sides are the 

 necessary locations to strengthen the stem or branch. 



In this article, the results of bending experiments with six five- 

 year-old ashes are given, these having been in progress from May to 

 November, 1912. Three of the ashes were bent to the east — one 

 all the time, the second only on alternate days, and the third on 

 alternate weeks. The fourth tree was tied to the east or west on 

 alternate days, and tree five on alternate weeks. At the end of 

 the season each trunk was cut into five sections, usually at the 

 base of each year's growth, and the increment for 1911 and 1912 

 measured on the base of each section along the north, south, east 

 and west radii. 



The data from the first three trees showed for each tree, the 1912 

 ring on the west or convex side from 2 to 3 times the breadth of the 

 ring on the concave side, taking the average of the five sections. 

 In the case of trees four and five, the average growth on the east 

 and west sides was equal, in keeping with the alternate bending. 

 Comparison of the amount of growth on the east and west sides 

 with that along the neutral north and south radii brought out the 



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