1896. ] Growth of Banana Leaves. 369 
The first thing to which attention is called in this table is 
the mode of development. In the first place, a striking uni- 
formity of growth is noted, and at the same time a gradual 
increase in the tree’s capacity of assimilation, which is shown 
by the gradual increase in the ‘‘mean daily surface growth” 
from leaf I up to IV. I will state that these observations 
were made on one banana tree only, in order to exclude in- 
dividual errors arising from the differences in individual trees, 
and that the four leaves were developed one after the other. 
This statement enables me to explain that the gradual in- 
crease in the daily surface growth from I to IV is due to the 
increasing area of assimilating surface. Each succeeding leaf 
has the last additional one to assist in gathering food for its 
growth, and the work goes more rapidly. 
The increase in the rate of assimilation with the addition of 
new leaves is less than I expected to find. It is not in any 
way proportional to the increase of leaf surface; and this sug- 
gests that the chief burden in the work of making the next new 
leaf lies upon the previous leaf that was made. This is also 
further Suggested by the banana tree’s mode of growth. The 
anana appears to have only one center of growth and elabor- 
ation; it makes only one leaf at a time, and practically com- 
pletes one leaf before it begins with the next. Many other 
trees are producing scores of leaves at the same time, showing 
that centers of work are distributed over the tree’s complete 
rganism. Moreover, the full grown leaves of the banana are 
‘oon frayed out with the wind and rendered useless for work, 
Which forces the work of assimilation upon the new leaves. 
The details in the tables also show strikingly the variation in 
the rate of growth along the period of development. e 
Young leaf begins slowly, daily increasing its rate of increase 
Up to the Stage of its maximum power of growth, where it 
‘attics for two or more days, until the leaf, which hitherto 
has been almost as tightly rolled up as a cigar, begins to un- 
fold to the light, when the rate of growth falls off till it is 
full stown. In the history of the four leaves this mode of 
sTowth is seen to obtain. : 
One other striking truth set forth by the daily data of de- 
Yelopment is the difference between the growths of the ‘‘day 
“nd “night” periods. The observations were continued upon 
leaves III and IV not only to compare the results of the day 
and night growths, but also to note the results of variations 
