1912] BRUSH—MECHANICAL TISSUE 465 
Contact-pressure in this case seems to play a comparatively small 
part. 
TABLE V 
PERIOD 37 DAYS 
UNDER TENSION TENSION-FREE CONTACT-FREE 
Tendril Final wt. tm Tendril Final wt. poten ng Tendril pres y 
Ag 1cograms| 460 grams A, | Ioograms| 350grams As II5 grams 
Ay 20 190 Ac 120 
C, 100 1150 Cy} 00 300 
C, 20 1160 C,; 20 300 
C; 20 1075 Ce 20 235 iG oi. aisle 
D, 100 075 D, | 100 325 
D, 20 210 
De 20 1385 D; 20 275 
D, 20 a75 
E; 20 780 E, 50 350 
E, 20 185 
F, 7° 235 
G,; 109 1200 G, | I00 350 
G, 20 1465 
G; 20 III G; 20 210 
G, 20 12490 
H, 50 225 
H, 20 II0o H; 20 300 H, |\ 160 
H; 20 925 He 20 190 He 140 
Averages 1073 265 ee 
* This tendril had ligature only. 
4. Pressure-—Another method of separating the influence of 
contact from that of tension consisted in allowing the tendril to 
twine about a piece of pure rubber tubing, which is very elastic, 
and after the coils had become firm, to apply pressure inside the 
tubing by means of a column of mercury. A single thickness of 
pure cellulose paper was wrapped about the tube to prevent any 
poisonous effect upon the tendril. In order that the tendril might 
grip the tubing tightly, so that the pressure could be applied effect- 
ively, the tubing was doubled upon itself radially and fastened by 
a few turns of cord; as soon as pressure was wanted, this cord was 
cut, which put the tendril and rubber in close contact, so that very 
little of the pressure from the column of mercury would be taken 
up by the rubber. The effectiveness of this method was aided by 
the contraction which takes place in the tendril after the coils 
have formed (Firrinc 7). It was calculated that a height of 
