92 



The Philippine Journal of Science 



variability differed from day to day. If, for example, on one 

 day a certain plant shows a very great increment, as compared 

 with the increments of the other plants, does it show high 

 relative increments on the other days? An answer to this ques- 

 tion is brought out in Table 4, which shows the increments of 

 total leaf elongation for each plant for each twenty-four-hour 

 period, each increment being expressed as a percentage of the 

 average increment for all plants for that day. 



Table 4. — Increments (for each of the five days) in leaf elongatk 

 the twenty-four-hour period, these increments being expressed a 

 centages of the average of the ten plants for the day. 



for 



Day. 



Plant 



Plant 



r, r 



"r 



«... 



Plant 



V 



r r 



P , r 



",r 



First 



m 



1 



36 

 34 



« 



c) 



111 



i 



5 



■: 



1 











Minimum 



tit 



115 



: 



:» 



!-' H 



2?5 



£ 



« 



i« 



I™ 







Table 4 shows that from day to day there was great variation 

 in the relative rates of elongation; a plant may on one day 

 show leaf elongation much below the average for all plants on 

 that day, while on another day it may show an elongation 

 greatly above the average. Thus it would be impossible to 

 standardize each of these plants on one day and to predict their 

 relative increments on a succeeding day. It is true that plants 

 2 and 3 always gave a relatively small daily increment, and that 

 plants 1, 5, and 6 gave relatively high increments on most days; 

 but their relative increments were not at all constant, and other 

 plants varied, during the five-day period, from very low to very 

 high relative increments. 



In order to bring out possible relationships among the four 

 different kinds of plant data, the data of Table 1 were re- 

 arranged to form a new table, in which the first vertical column 

 gave the growth increments in a descending series, beginning 

 with the largest day increment and ending with the smallest 

 day increment. The table was then completed by placing in 

 the second, third, and fourth columns, respectively, the night 

 increment, the twenty-four-hour increment, and the ratio of 

 the night increment to the day increment, corresponding to each 

 of the day increments in the first column. The values in each 



