The Influence of Correlation upon the Size of Leaves. 
BY 
ALFRED J. EWART, D.Sc., Ph.D., F.L.S. 
With two Figures in the Text. 
A CCORDING to Lindemuth 1 , leaves of Begonia rex and of Iresine 
Lindeni which have been allowed to root in soil increase in size, and 
this increase is due not to any multiplication of cells but to an enlargement 
of the individual cells. It remains an open question whether the enlarge- 
ment is directly due to a rise of turgor in the extensible cells of the leaf, 
or whether it is a true growth reaction awakened by some correlative 
influence. In any case it seemed of interest to determine whether a similar 
expansive enlargement can be produced on the leaves of an ordinary tree 
after they have ceased to grow, and a lime tree ( Tilia europaea) was 
selected for the experiment. 
On April i, all the buds were removed from a branch 145 cms. long 
and 3 cms. diameter at the base, excepting the terminal one, and new buds 
were removed as fast as they developed. The branch produced 31 times 
as many buds as would normally develop. Measurements in centimetres 
of the leaves were taken on June 27, the length and breadth of the lamina 
being those of an inscribing rectangle traced 
i on paper (Fig. 
i ). At the 
same time an average was taken of the larger 
also of the smallest first formed ones. 
leaves on normal shoots, and 
Lamina. 
Defoliated Branch. 
Petiole. 
Breadth. 
Length. 
Internode. 
1st leaf ..... 
3 
6*2 
7 
0-5 
2nd leaf ..... 
4*5 
7.8 
8.1 
3rd leaf ..... 
5.2 
11 *5 
14*2 
I# 5 
4th leaf 
5.0 
11*2 
15 
3*2 
5th leaf 
4-2 
1 2-5 
17.1 
4.7 
8.1 
8*6 
6th leaf ..... 
3*5 
13.2 
16-2 
7 th leaf 
Normal Branches. 
^•5 
13.2 
j6-8 
Average of largest adult leaves . 
4.4 
7*7 
10*1 
4*5 2 
Average of smallest adult leaves 
3‘° 
3.2 
2-8 3 
1 Ber. d. D. Bot. Ges., xxii, 1904, p. 171. 
2 
Average on 
largest normal shoots. 
3 Average on smallest normal shoots. 
[Annals of Botany, Vol. XX. No. LXXVXI. January, 1906.] 
