23,1 T release: Elongation of Banana Leaves 39 



5 for the fifth day, in which case the rates are clearly very 

 exceptional. No special explanation for the exceedingly high 

 rates of this plant for that day is suggested ; and the day, night, 

 and twenty-four-hour values for plant 5 have been disregarded 

 in the computation of the average rates for the fifth day. In 

 all other cases the daily averages given in Table 1 are derived 

 regularly. 



The mean increments in elongation for the five night periods 

 were 3.8, 3.4, 2.4, 2.3, and 5.0 centimeters, respectively ; for the 

 preceding day periods they were 2.7, 1.5, 2.5, 1.2, and 2.3 

 centimeters, respectively; and for the twenty-four-hour periods 

 they were 6.5, 4.9, 5.0, 3.5, and 7.3 centimeters, respectively. 

 Aside from the exceptional case just mentioned, the greatest 

 total leaf elongation for the twelve-hour nocturnal period was 

 14.4 centimeters (plant 6, fifth day) , the greatest for the diurnal 

 period was 9.2 centimeters (plant 1, first day), and the greatest 

 for the twenty-four-hour period was 20.7 centimeters (plant 

 1, first day). The smallest elongations were 0.2 centimeter 

 for the nocturnal, zero for the diurnal, and 0.2 centimeter for 

 the twenty-four-hour period. 



Although these rates of elongation may be considered as rep- 

 resentative of what may be expected for banana leaves under 

 environmental conditions similar to those here dealt with, the 

 growth rate must in general be more or less markedly influenced 

 by the climatic conditions (generally grouped as climate, season, 

 and weather), as well as by the internal conditions of the plant 

 (usually grouped as the variety of plant; its tone, or health 

 condition; and its phase of development). The pronounced 

 variation shown in the elongation rates given in Table 1 may 

 possibly have been due to corresponding variations in the envi- 

 ronmental conditions, or they may have been directly related to 

 internal variability among the plants themselves. Both groups 

 of conditions may of course have been influential together. 



An attempt was made to find out whether the growth data 

 contain any evidence of influential differences between the ex- 

 ternal conditions of the several days. The question is, do the 

 five days group themselves as good, poor, etc., for leaf elonga- 

 tion as indicated by the whole group of plants taken together? 

 One way to approach this question is simply to examine the 

 averages. Table 2 presents the five daily averages for each 

 of the four kinds of data, each series of averages arranged in 

 the descending order of magnitude. 



