Maxwell, The rate and mode of growth of Banana leaves. 



The averages are as follows: 



The first thing to which attention is called in this table is the 

 mode of development. In the first place, a striking uniformity of 



iwth is noted, and at the same time a gradual increase in the 

 trees' capacity of assimilation, which is shown by the gradual in- 

 in the „mean daily surface growth" from Leaf No. I up to 

 No. IV. I will State that these observations were niade on one 

 banana tree only, in order to exelude individual errors arising from 

 the differences in individual trees, and that the four leaves were 

 developed one alter the other. This explanation enables me to 

 i xi ilain that the gradual increase in the daily surface growth from 

 No. I to No. IV is due to the increasing area of assimilating surface. 



■h succeding leaf has the last additional one to assist in gathering 

 food for its growth, and the work goes moore rapid ly. 



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 suggests that 



the chief burthen 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 trees mode of growth. The banana appears to have 



only one center of growth and elaboration ; it makes only one leaf 



a time, and practically completes one leaf before it begins with 



the next. Many other trees are producing scores of leaves at the 



.^anic time, showing that centers of work are distributed over the 



trees complete organism. .Moreover, the füll grown leaves of the 



banana are soon frayed out with the wind and rendered useless 



for work, which leaves the work of assimilation to the new leaves. 



The details in the tables also show strikingly the Variation in the 



rate of gr< wth along the period of development. The young leaf 



begins slowly, daily increasing its rate of increase up to the stage 



maximum power of growth, where it tarries for two or more 



ä, mitii the leaf, which hitherto has been almost as tightly 



ed up as a cigar, begins to unfold to the light, when the rate 



growth falls oi tili it is füll grown. In the history of the four 



this mode of growth is secn to obtain. 



< >ne other striking truth setae forth by the daily data of develop- 



nl is the difference between the growths of the „day" and 



„night" periods. The observations were continued upon the leaves 



