124 Bateson . — On the change of shape 
In the case of Impatiens Sultani the transverse extensibility 
is so great that transverse expansion is not only clearly 
apparent from the first, but is never overcome by the longi- 
tudinal expansion — the pith continues to expand transversely 
and never exhibits a subsequent contraction. 
If the transverse extensibility of the cell- walls in Impatiens 
is so great relatively to the longitudinal extensibility, we 
should expect to find the longitudinal extensibility in Impatiens 
small in comparison with what it is in the Sunflower and Elder. 
The following figures show that this is the case. 
Longitudinal Expansion of Pith when placed in water, given 
in per-centages of the original length. 
Sunflower (i) 14*3 p. c. after 2 hrs. 38 min. immersion. 
( 2 ) 15-9 
}> 
5 
9 > 
50 
Elder 
(1) 9*5 
>> 
1 
99 
50 
(2) 16.9 
»> 
2 
99 
0 
(3) 16.8 
2 
99 
H 
Impatiens 
(1) 4.0 
)> 
1 
99 
30 
(2) 4*4 
2 
99 
16 
(3) 5*9 
>y 
3 
99 
6 
(4) 3*i 
4 
99 
23 
If we express the relation between longitudinal and trans- 
verse extensibility by the fraction y,, we can place the tissues 
with which we are acquainted in the following order. 
(1) The highest value of occurs in those cases (e.g. in 
experiments 1, 2, 4 under Elder and Sunflower) where no 
preliminary expansion occurs. 
(2) fp is of lower value in the case of Rhubarb where a 
preliminary expansion always occurs. 
(3) of still lower value in Impatiens Sultani where no 
transverse contraction takes place. 
(4) L rf of lowest value where, as in roots, T is greater than L, 
and produces a longitudinal contraction. 
