1922] EVANS—GERMINATION 217 
set for Indiana seeds collected in 1915 and untreated, another for 
Washington seeds untreated, etc. Eleven sets of curves were thus 
plotted, three of which are included in this paper as fairly typical 
ones. Not fewer than two hundred seeds of each type were 
germinated at each temperature, one hundred each in a separate 
Petri dish, so that all determinations were made at least in duplicate. 
In some instances four hundred seeds of each type were used, 
making quadruplicate determinations. 
From these curves, three sets of which are given as typical, the 
length of time required for certain percentage germination at two 
different temperatures was read, and these readings and temper- 
atures used in the Kanitz formula: Q,.= is t-t , in which k,= 
rate of germination at temperature t,, and k,=rate of germination 
at temperature t,. The rate of germination in each case of course 
was the percentage germination divided by the number of hours 
required for this to take place. The results of these computations 
are given in tables I to XI. oo 
Again similar experiments were run and attempts made to secure 
lots of seeds at the same percentage germination with hypocotyls 
the same length when the seeds were subjected to different tempera- 
tures. These readings were used exactly as were the ones from the 
curves previously mentioned, and as they gave the same type of 
coefficients, for the sake of brevity are omitted here. 
TABLE I 
INDIANA SEEDS, COLLECTED 1915, UNTREATED 
Qo at certain percentage germination* 
Temperature 
interval (° C.) 
12 14 20 28 30 4° 50 60 7° 80 
AS gedit corre ego ES OOD TAISE OTTO Coie eis bs els mie cnke des oe 
ag ok ee eee) Gree 2: Q5) 5.05] 2.04) 4.971 3.08) 4.08... fo ests sa os 
MSs SA Cee +. 73] 1-76) 1.83} 2.6 : 2.011 2 2.04) 2.91 
LED gg) © Set ee unas Buc 1.14] 1.13| Less} Less} Less} 1.14) 1.28) 1.49} 1.37 
than} than) tha: 
I I 
OE ge ee ties Pa ane ne sa EE 2.001 2. 98t.4 6.5 OOK) BSE O. FAL. ocho vile ns cs 
BOOS Oia ies 1.68) 1.72| 2.11] 2.02] 2.29) 2.41] 2.96) 2.94] 3.53 
* No germination at 8°-10° in 168 hours. 
