268 BOTANICAL GAZETTE [OCTOBER 
experiment. One-half of the shoots were removed and tested January 
25,1. ¢., after 16 days and subjection to a maximum tension of 4508". 
Table VI, record A, gives an average of the results for this part of the 
experiment. The average breaking strength is slightly increased in 
the experimental shoots. 
The remaining shoots were tested March 2, 1908. An average 
of breaking strengths as given in table VI, record B, shows an increase 
in favor of the experimental shoots of 1.25" or 18 percent. A study 
of the anatomical structure of these stems was made by methods 2, 4, 
and 5. These determinations show an increase of 30 per cent. in 
the entire xylem area, an increase in xylem wall thickness of 13 per ‘ 
cent., and the same increase in the thickness of the walls of the hard 
bast fibers. A count of the hard bast fibers showed no increase in 
the number of these elements. 
Experiment 11. Ricinus communis, field culture—The method 
in this experiment was the same as in experiment 2. The tension fas- 
tening was placed just below the second pair of leaves. The control 
plants were not supported. The experiment began July 20 and 
ended August 1. A tension of 300%™ at the beginning was gradually 
raised to 2350%™ two days before the experiment ended. 
TABLE VII.—Ricinus communis 
< lz i 
e ez s 2 @ Fo n 
: E 4 o BS§ = oe 
Height to Chie at Diam. just § cay eX 2s 
2d pair of wh ah above 1st 2 on 2. | Bay 
. base in : bo oes ove 
leaves in panel pair of leaves| & Zeck 5 2 =e E 
cm. in mm. tas 6 - og | ks 
PE | Bae) Be | z 
a IR * : 
July | Aug. | July | Aug. | July | Aug. | Aug. | Aug. | Aug. gens 
20 I 20 I 20 ‘ I I ee 038 
16.25 Ey aS a § 8.18)}12.18)10.66 13.01/43 86/10. 24 21S 
16.4 |19.6 | 8.44/11.41| 9.95|12.56|41.22/10.4 25-99|2-929 
eee See prs teat 
| 
The average results, given in table VII, show 43.86** as the aver 
age breaking strength for the experimental plants and 41.22%8 for 
the controls, or 6.4 per cent. The increase is slightly greater than 
the final weight which was attached to the experimental plants. 1° 
average xylem wall thickness and total xylem area, as determined by 
methods 2 and 3, show an increase respectively of o. 1# and 4 per cent. 
or ee ee See > er oe 
a: 
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Se Oy Mee RPT ee pe Emer NT ome ey et tie ten RE Pt RR ae a ee ee ee 
