264 



Journal of Agricultural Research 



Vol. VI, No. 7 



In figure i the percentages of hydrocyanic acid in the whole plant are 

 plotted against the age in days. No noteworthy differences were no- 

 ticed when the height of the plants was used instead of the age in days. 



Figure 2 represents the growth curve of the various plots, where the 

 height in centimeters is plotted against the age in days since sprouting. 



In order to study the relation between climatological factors and the 

 content of hydrocyanic acid, figures 3 and 4 were constructed. In 



Fig. I. — Curves showing the hydrocyanic-acid content of sorghum on the various plots. (Percentage of 

 hydrocyanic-acid computed to drj'-matter basis.) 



figure 3 are plotted first the precipitation (in inches) during 15-day 

 intervals; second, the temperature (degrees Fahrenheit), using averages 

 for lo-day periods, and, third, the mean relative humidity (percentage) 

 at 6 a. m., all for the five months May to September, inclusive. In figure 

 4 the history of each plot for the season is shown and includes the rain- 

 fall, temperature, and hydrocyanic-acid curves on the same graph. 

 The dates for planting, sprouting, appearance of seed panicles, and 

 irrigations are also shown. 



