254 ; M. A. de Candolie un Germination 
perature of 27° to 28°. At the end of thirty-one hours, one seed 
germinated. The experiment was not continued. 
Temperature of 40° to 41°. 
The seeds were sown on the 6th of August, at 8 p.m., in a 
glass vessel, filled with dry sand, placed in the centre of the 
porcelain cup containing the moist sand of the preceding experi- 
ment. At 11} p. m. I watered them freely with water at 41° 
which had not been boiled, The temperature of the sand was 
maintained, until the 10th of August at 54 p.m., between39°6 and 
4.5°°4, but it only rose to this temperature in the evening of the 
7th of August, and the mean, taken every twelve hours, was 4.0°°6. 
Two seeds of Sesamum germinated at the end of ten hours and 
a half, and others followed immediately. The mean during these 
ten hours and a half must have been 40°°7. None of the other 
species germinated ; and as the seeds of the maize and the melon 
had assumed a dark tint (especially those of the maize), which in- 
dicated a change, I removed the glass vessel and placed it upon 
a marble mantlepiece, where it rapidly acquired the surrounding 
temperature of 20° to 21°. To my great surprise, four hours 
and a half afterwards, three melon-seeds germinated! The other 
species did not sprout during the following days, up to the 12th 
of August; it is thus probable that the melon-seeds would have 
germinated at 40°°6,if I had not interrupted the experiment. 
They would then have required, under these conditions, four days 
winus two hours, or ninety-four hours. 
At higher temperatures. 
It appeared to me useless to continue the experiments at higher 
temperatures, except as regards Sesamum, which seemed best to re- 
sist an extreme heat. The experiments of Lefébure, as well as of 
Edwards and Colin, have proved that most seeds undergo a change 
at temperatures of 50° and upwards when the soil is moist—a 
change so great that they are incapable of germinating when 
subsequently placed under favourable circumstances. Seeds 
heated in the dry state in a stove are capable of bearing a heat ap- 
proaching the point of combustion* ; but in water they lose their 
power of germinating at 55° or 50°, and perhaps below, accord- 
ing to the species, and especially according to the duration of the 
immersiont. In moist earth the seed is changed, according 
to the abundance of water, at various degrees of the thermo- 
meter. Thus, with the method of experimenting which I had 
adopted for a certain purpose, the seeds, always being copiously 
watered, would lose their power of germinating at 50°, 45°, and 
* Edwards & Colin, /.c.; Théod. de Saussure in the ‘Mém. Soc. de 
Phys. et d’Hist. Nat. de Genéve, iii. part 2. 
+ Lefébure, p. 120 e¢ seg.; Edwards & Colin, J. c.; Fr. Burckhardt, J. ce. 
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