32 
(Mt) TEMPERATURES FROM 40° To 41° Cc. 
Two Sesamum seeds germinated in 104 hours under 40.7°, and the 
cthers immediately after; 3 J/elon seeds germinated in 94 hours 
under 40.6° ; none of the other seeds germinated at all in 4 days. 
(N) HIGHER TEMPERATURES. 
MM. Lefebure (1800) and Edwards and Colin (1834) have shown 
that most seeds undergo an alteration at a temperature of 50° C., so 
that they will not germinate after that, even when put under most 
favorable conditions. Some seeds when kept dry can be warmed in a 
stove almost to the point of combustion, but in water they lose the 
power of germination at 55° or 50°, or perhaps lower. In humid 
soil the seed is altered in proportion to the abundance of the water 
and the temperature of the soil. Thus, in De Candolle’s above-given 
experiments, the seeds being kept quite wet could lose the power of 
germinating under 50° and perhaps under 34°, as some of the pre- 
ceding experiments show, without, however, precisely defining this 
limit. Therefore De Candolle only experimented on the seeds of 
Sesamum at high temperatures with the following results: The 
temperature varied from 50° to 57° C. The seeds were watered 
copiously. One seed in 5 germinated in 25.7 hours at an average 
temperature of 51.5° C. On repeating the experiment, 3 seeds in 12 
germinated at the end of 6 days, and 2 subsequently, but the majority 
did not germinate, the temperature having averaged 44° C. during 
the first 26 hours and 20° C. during the remainder. 
For ease of study I have collected most of De Candolle’s results for 
cach of the eleven plants, respectively, into the following smal! tables: 
a 
Tables showing results of De Candolle’s experiments on the germination of seeds 
at different temperatures. 
LEPIDIUM SATIVUM. 
Temper-| « | Temper . Temper-| -m: 
ris | Time ature Time. ature. Time. 
| " | 
een, | °C, Hwaeeeae 
1.8 | 30 days. 9.2 | 8 days. 26.5 | 16 hours. 
2.9 | 12 days 12.9 | 1.75 days. | 28.0 | 89 hours. | 
5.3 18 days 17.05 | 1.5 days 
| 5.7 | 5 days 21.1 | 38 hours | 
SINAPIS ALBA. 
ate | | | alae 
| 0.0 | 17 days. | 9.2 | 3.5 days. 25.05 | 36 hours. 
1.9 | 16 days. | 12.9 | 41 hours. 28.0 | 72 and 78 
2.9 | 9 days. 17.2 Do. | hours. 
4 
| 4 days. 21.1 | 22 hours. 
I| 
