290 maine agricui.turai, experiment station. i914 



Growth and Variation in Maize.* 



This paper gives the results of a study of the growth of the 

 sweet corn plant and the relation of the growth phenomena 

 exhibited to the laws of variation of the plant. 



1. Measurements were made at twice-a-week intervals of the 

 height of three series of corn plants. The heights were meas- 

 ured to the tip of the tallest leaf. In addition to these, separ- 

 ate sets of measurements were also made of the tassel height as 

 soon as the tassels appeared, 



2. The growth curves obtained by plotting the mean height 

 at each measurement are relatively smooth. 



3. After July 3, the time of tasseling, the plants grow in 

 height much faster than before. Growth in height ceases en- 

 tirely as soon as the tassel blooms. 



4. The absolute variability shows a marked increase up to 

 about June 19. From this until the time of tasseling it remains 

 nearly constant but shows a very great increase at the time of 

 tasseling. After all the plants have tasseled the absolute varia- 

 bility decreases somewhat. 



5. The relative variability considered for the whole season 

 shows a marked progressive diminution. It thus follows the 

 general growth law of diminishing variability. Considered in 

 detail, however, the relative variability first shows an increase. 

 After June 19 there is a rapid decrease until the time of tas- 

 seling. During the period of tasseling there is a very rapid 

 increase in the relative variability. This is followed by an 

 equally rapid decrease. A stable condition is finally reached 

 which is some ten per cent, lower than the variability at the 

 beginning of the season. 



6. It is interesting to note that the relation of tasseling to 

 the growth and variability of the height of corn plants is not 

 unlike the relation of puberty to the growth of children. This 

 does not mean that the two processes are necessarily analogous 

 physiologically. 



7. From the data presented it appears probable that the 

 corn plant grows in a series of cycles. Each cycle is character- 

 ized by the special development of one set of organs. They are, 



*This is an abtsract of a paper with the same title by Raymond Pearl 

 and Frank >M. Surface, now in press in Zeitschrift fuer induktive Abstam- 

 mungs-und Vererbungslehre. 



