jane i4 ,1924 Influence of Environment on Sex in Hemp 1075 
tion was terminated long before the flowering stage was reached, it is not possible 
to say whether this lot would have bloomed sooner or later than those which 
were grown in the normal summer day length. The writer is inclined to believe 
that there would not be much difference. But with such a curve it is possible 
to predict the time that buds will appear with considerable accuracy, especially in 
the shorter exposures. Several times the writer has planted hemp when the 
Hours light daily 
Fig. 3. Graphshowing the relation between the number of days from planting to flowering and the number 
of hours of light received daily. Ordinates indicate 5-day intervals from the time of planting and abscissae 
indicate the number of hours of light received daily. Hemp can not be grown to the flowering stage 
in less than 3 hours of light daily 
period of daily illumination was about 9 hours and has been able to predict 
within one day of the time when flower buds would appear. 
An increase in the length of daily exposure to light after the flower buds appear 
has been found to greatly affect their further development. In an experiment 
carried on in the greenhouse during November and December it was found that 
flower production could be checked by increasing the period of illumination. 
Three plats were used. Plats two and three were given the normal daylight for 
that time of the year, but plat one was given, in addition, illumination from a 100- 
watt electric light from 4 to 8 p. m. every evening. On December 19, flower buds 
appeared on the plants in plats two and three. At this time the hemp in plat one 
