1922] EVANS—GERMINATION 221 
TABLE XI 
INDIANA SEEDS, COLLECTED 1914, GROUND WITH SAND TWO WEEKS 
i Qo at certain percentage germination* 
Temperature 
interval (° C.) 
22 30 40 50 60 7° 80 
12.0 140450005510 O15 8.88 8.30 8.001 6.65 LT AS 
4 AS52346 3.58 3.58 3.84 4.19 4.54 4.91 5.40 
23.4 36,4705... 1.02 I.QI 1.89 1.89 1.92 1.88 1.68 
Ocd Ale oe cs les oe be Ti 24 a3 1.18 I.1I0 1.06 £35 
TEAS 766. ZY 20% 3.24 3-72 3.94 4-35 
2354-20 .0505..- 1.03 1.97 cid 2.09 Dae aie Sen Mcehinen) Gane retreats 
14.45-36.4..... 2.44 2.48 7.53 2.61 2.75 2.79 2.92 
* 5 per cent germination at 8°-10° in 168 hours. 
Discussion 
In the effort to find a representative end point, many different 
ones were tried, with the result that almost any one proved satis- 
factory. These end points are Q,, at different percentage germina- 
tion. A study of the tables shows that almost any percentage 
germination up to the total at the temperature might well serve for 
this representative end point, as in practically every series the 
coefficient for 10° C. rise in temperature is more than three when 
computed at temperature intervals near the minimum temperature 
for germination, and gradually decreases to about one or even less 
than one near the maximum. At some range between these, of 
course, Q,, falls between two and three. It is interesting that by 
computing through a long temperature interval Q,, may be found 
to be between two and three, when computations over shorter 
intervals of this longer one show Q,. not a constant but a variable. 
Take, for instance, from table III Q,, at the range of temperature 
14.45 —36.4°=2+, while Qyo at 14.45°-23.4°=3.6 to 4+, 23.4°- 
36.4°=1.8 to 2.0. Here Q,, computed through a long interval 
where its values range from 4 to 1.8, gives an average value of 2+. 
This is the sort of thing to which Kanrrz called attention. The 
series of coefficients computed through short temperature intervals 
agrees in general type with those given by Lerrcn for effect of 
temperature on rate of growth of seedlings of Pisum sativum, with 
those given by LEHENBAUER for rate of growth of corn seedlings in 
