June 14,1924 
Influence of Environment on Sex in Hemp 
1073 
Although the extent of growth was greatest in the longer light exposures, it 
does not necessarily follow that this result is due to a higher rate of growth ov< r 
the entire period. In fact, the data show that in 7 or 12 hours of light daily the 
rate of growth at certain times equaled or even exceeded the rate of the 24-hour 
lot. The greater height at maturity in 18 or in 24 hours of light daily exposure 
Fig. 2.—Graphs showing relation between relative length of day and night and growth in hemp. The 
seedlings were 5 cm. in height when the experiment was begun. Ordinates indicate growth in centi¬ 
meters and the abscissas indicate the number of days. The numbers at the end of each graph 
show the number of hours of light received daily by each lot of plants. Measurements were made 
every two days 
is due to the high rate during the early part of the growth period and the con¬ 
tinuance of this rate over a long period of time. If the growth rate which the 
7-hour plants have just prior to anthesis could be maintained over a long period 
they too would be tall but the period of this rapid rate of growth lasts but a few 
days and then rapidly declines to zero. Since hemp in this exposure grows rela¬ 
tively slowly up to the time of anthesis and then rapidly for only a short time, it 
necessarily follows that the plants will not attain a great height. The high growth 
