12 BOTANICAL GAZETTE [JULY 
a slight increase in germination. Still more interesting facts are 
brought out by the frequency histograms (fig. 3), from which are 
evident the value most frequently appearing for the carbon dioxide- 
oxygen ratio, and the total variation of this ratio in the entire 
number of experiments on each seed. In plotting these histograms 
the values for the quotients were grouped, and since it was found 
that experimentally and mathematically the digits for the quotient 
45. 
= 
"| ie 
20. 
mg O2 
bb 
ow CO, /o2 
os 4 
ee ee eee es ie 
A th 3 
R 
horizontal axes represent time in days after harvesting: vertical axes represent values 
from 0.5 to 4.5 for the CO,/O,, these being absolute numbers indicating ratio; for 
“respiratory intensity” curves represent mg. of gas per gram imbibed weight of 
seeds per 24 hours. 
are significant only to hundredths, the interval between these 
groups or classes was taken as 0.01. 
The range of the value of this ratio, as determined by the 
maximum and minimum, varies widely in the different seeds, being 
least in Amaranthus (0 .685-0.975, that is, 29 classes) and widest in 
hawthorn (0.470-1.140, that is, 67 classes). In Chenopodium 
the heaviest grouping lies within a range of only seven classes, but 
between the lower limit of this group and the next lowest quotient 
is a gap of nineteen classes, while above the group’s highest limit 
