1909] BORDNER—INFLUENCE OF TRACTION ON STEMS 267 
were no longer elongating would respond to tension by increasing 
their breaking strength. For this reason, shoots older and larger 
than those in experiment 8 were used. The controls were supported 
as in experiment 8. A weight of 200%™ attached to the experimental 
shoots on November 15, 1907, was increased to 400%™ on December 
14. The experiment ended January 8, 1908. 
The third instead of the last internode below the tension fastening 
was tested for its breaking strength. No elongation and in many 
cases no growth in diameter took place in this internode. An average 
of the breaking strengths shows no response to tension for an internode 
which is no longer actively growing. 
TABLE VI.—Vinca major 
Recorp A 
2 SSE ac EE, —=- aioe mee ; 
| we laeel| So = / g g 
| par 32 |eti 2 |g | £2 | 2 
| | Height to | nam just| ~e |oe8] # $8 Pe oe n 
+ | * - Just Mite: Ss o= ey 2a 
No. of Height in ore et below 33 os 2 Ae 5 x) = 23 5 EE 
Plant | cm, Siepouskd fastening | fo | 88'S) Ga laee| #7 | eoel| wo 
fastening rsh we | eo) 2 ese} ae | EB Ca 
: in cm. C8 |Smu/ 3 os 22 we . 3 
| in em, sa |2ee| Bs |2 a a 258 64 
| Fa a = o 2 a A 
Bel | | | Be BPSATS rai! 
Jan. | Jan. | Jan. | Jan. | Jan. | Jan. Jan. 
Pat 9 25 ° 25 9 25 | 25 } 
AY. . “|29- |41.4/25.6/27.3 2.11|2.22| c ereaet 8.25 ee ee bipage. pee e eee: 
Control | | | 
Vi, aa \44- /28 4/29 6/2 og}2 70) : 8.75 pee. | peers | Par er ke ie er Se a Be 
A eg shee | ey ee Be Peeirees Were: ae Vinee SAR LT Ps. a ee eee ea 
Recorp B 
l Sopsees WED a 
I Mar. | | Mar. Mar | | Mar. | Mar.| Mar. | Mar. | Mar. _ 
Exp. rest et byes es 2 fe 
BY: . -|29.2195. 2 del bag sad act dese 15 | 8.22] 5.77] -2777| 7-42 | 127 
Control | | } | 
Ay. + |28.6)62 26.|28.5 as 2.321 eo 52:3 6-97 509) ae 6.56 | 1297 
| | i Berens 
Experiment 10. Vinca major, greenhouse culture.—This experi- 
ment was in large measure a repetition of experiment 8. -Tension 
fastenings were madé on all the shoots. Just enough weight was 
attached to the control shoots to hold them erect. The experiment 
began January 9, 1908, with a weight of 250®™ attached to the experi- 
Mental plants. This was increased to 450%™ eight days later, and to 
gooe™ January 25. The internode to which the tension fastening was 
attached was in each case actively elongating at the beginning of the 
