KNOT ZONES AND SPIRAL, IN ADIRONDACK RED SPRUCE 785 



begun. The second study took into consideration spiral of the most 

 severe type by making the measurements on the basis of exact per cent 

 measurements. Classification of spiral in the first field study recognized 

 five distinct classes, the poorest being one inch of departure from the 

 axis of the tree in 15 inches of length. All trees exhibiting a more 

 severe twist of fiber than this were all thrown into one class. 



While the measurement of degree and direction of spiral was made 

 at the center of the first log on all trees, it was noted that few trees 

 maintained this same degree of twist throughout the length, and that 

 many changed even the direction from left to right or, more rarely, in 

 the reverse order. 



It was observed early in the field study that the trees of larger diam- 

 eter had a predominantly right spiral, while the smaller classes twisted 

 to the left. Figure 4 is presented to bring out this fact and also to show 

 an interruption in the tendency. At the right of the diagram are shown 

 the numbers of trees measured in each diameter class. The vertical 

 co-ordinate shows the diameter classes and the horizontal co-ordinate 

 shows in per cent the total number of trees in each class, the excess of 

 left over right spiral, or vice versa. It may be noted in the left-hand 

 diagram that up to the 6-inch class there was an excess left spiral and 

 beginning at 7 inches an excess number spiraling to the right. A break 

 is shown in the curve between the 11 and 12 inch classes. It must be 

 remembered that the points are secured by mathematical average, so 

 that a continuous curve cannot be logically drawn. The right-hand 

 diagram shows a similar presentation of data obtained at Brandreth 

 Lake and two quite distinct breaks occur in the curve, one of which 

 conforms in diameter class to that found in the other study. These 

 are interpreted to mean an interruption in the condition of growth, 

 especially light relation, due possibly to severe windfall. 



In figure 5 is shown graphically the amount of spiral in terms of 

 per cent of the total number of trees in each diameter-class group. On 

 the vertical line D, which represents a spiral of i inch in 20 inches, or 

 5 per cent curve, No. 3 shows 50^ per cent of all the trees over 14 

 inches in diameter meeting this specification. Curve No. 4 represents 

 all trees over 14 inches measured at Brandreth and shows 525/^ per cent 

 straigliter than i inch in 20 inches. Similarly curve No. 2, representing 

 trees 9 inches to 13 inches, inclusive, shows them generally straighter 

 than the larger ones, while curve No. i shows trees up to 8 inches less 

 spiraled than any other class. 



