at different Degrees of Constant Temperature. 26] 
hours) to germinate. Ten times 5°7 gives the number fifty- 
seven, but it has been determined that at 5°°5 the species no 
longer germinates; hence the truly useful temperature would 
be only 0°2 during ten days, which produces a total number of 
2° only. Similar calculations being made upon germinations of 
Trifolium observed at 9°, 18°, 17°, &c., have yielded as follows :— 
Calculating Deducting the 
Temperature. Days. above 0° minimum 5°°5. 
57 x 10 = 57 2 
Che 5 46 18 
13:2 3 39 23 
17:0 2°6 44 30 
1191 1°75 y/ B7/ 
25:0 I-75 44 34 
28°0 3 84 67 
In both methods of calculating, the first and the last numbers 
present a disparity with the others; 7. e. near the minimum and 
near the maximum the relation of the temperature to the duration 
of the germination differs from the ordinary one ; in other words, 
the germination is then more difficult and becomes extremely 
slow. Under the other conditions of temperature, the numbers 
do not present greater diversity than is admissible m physio- 
logical facts, where so many causes exert their influence and where 
errors of observation inevitably creep in. In opposition to what 
I had supposed, the numbers in the present instance differ more 
from each other if the useless temperatures are deducted than 
if this is not done. 
Lepidium, which requires about 1° to be able to germinate, 
gives the following numbers* :-— 
Calculating Calculating 
Census Tas Days. above 0°. above + 1°. 
IGort Xx 30 = 49 19 
3°0 11 33 22 
57 o 28 23 
Pe 3 28 25 
13°2 1-75 23 al 
17:0 1°50 25 24 
21% 158 33 32 
28°0 16 44 43 
Let us also take Sesamum, which requires a very high minimum, 
from: 10° to 12° (say 11°}— 
Calculating Calculating 
Temperature. Days. above 0°. above 11°. 
12°6 x 9 sain 4 0G 14 
16:9 3 51 ff 
Zi 14 29 14 
24°6 0:94 23 13 
28°0 0:92 25 15 
40°7 0°44 18 13 
* M. Burckhardt obtained higher numbers; but he regards as germina- 
