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The conclusions which De Candolle draws from his experiments are as follows:

(A) AT A CONSTANT TEMPERATURE OF 0° C.

From the 7th of March to the 11th of April-that is to say, in 35 days' exposure to this temperature the following seeds did not germinate at all: Collomia, Lepidium, Linum, Zea mays, Melon, Nigella, Sesamum, Trifolium, Celosia.

The only species which did germinate was Sinapis, the various seeds of which germinated in from 11 to 17 days, the latter seemed to De Candolle to be the more proper value of the time.

(B) AT TEMPERATURES FROM 1.4° TO 2.2° C.

Collomia and Celosia did not germinate in 35 days; Lepidium and Linum germinated in 30 and 34 days, respectively, under average temperature of 1,8°. Zea mays and Nigella did not germinate in 35 days; Sesamum did not germinate in 35 days; Sinapis germinated in 16 days, at an average temperature of 1.9°.

(c) AT TEMPERATURES VARYING BETWEEN 2.6° AND 3.2° C.

Collomia did not germinate in 36 days; Lepidium, about one-half of the seeds germinated, on the twelfth, sixteenth, and thirty-first days, respectively; Linum germinated on the seventeenth and eighteenth days, at an average temperature of 3.1°; Zea mays did not germinate in 36 days; Nigella did not germinate; Sesamum did not germinate. Three Sinapis seeds germinated on the ninth, one more on the seventeenth day. A new sowing of Sinapis gave one seed germinating on the sixth day. Afterwards the temperature was allowed to rise gradually, but the seeds which had not germinated before came to nothing.

(D) AT TEMPERATURES FROM 4.2° тo 6.1° c.

About one-half the Collomia seeds germinated on the seventeenth day, at an average temperature of 5.35°; Lepidium germinated abundantly on the eighteenth day; Zea mays did not germinate; about onefifth of the Linum seeds germinated on the seventeenth day (average temperature 4.8°); Nigella, Sesamum, and Sinapis did not germinate. Possibly the moisture was too large in series (c) and (D).

(E) AT TEMPERATURES BETWEEN 5.4° AND 6° c.

Some Collomia seeds germinated in 14 days; Lepidium germinated freely on the fifth day; Linum germinated freely on the sixth day; Zea mays did not germinate in 36 days; Nigella germinated in twentyseventh day; Sesamum did not germinate in 36 days; Sinapis germi

nated abundantly the fourth day; Iberis germinated the fourteenth day; Trifolium germinated the tenth day; Melon did not germinate in 36 days.

(F) TEMPERATURES ABOUT 9.2° c.

Collomia germinated in 63 days after sowing; Lepidium germinated the third day; Linum, 1 seed began to germinate the second day, several others the fourth; Mays, 1 seed germinated the tenth day, 2 others the twelfth day, and others afterwards; Melon did not germinate; Nigella germinated the fifteenth day; Sesamum did not germinate; Sinapis germinated at the end of 3 days; Iberis germinated the sixth day; some Trifolium seeds germinated the fifth day, others the sixth, eighth, etc.

(G) TEMPERATURES FROM 12° TO 13° c.

For the first three days the average temperature of the soil was 12.9°. The individual results were as follows: Collomia germinated from the sixth to the seventh day; Lepidium germinated after about 13 days (in a second experiment at 12.9° C. it germinated in 13 days as before); Linum germinated in about 2 days (in a second experiment at 13.5° it germinated at the end of 13 days); 2 Mays seeds out of 17 germinated at the end of the fifth day, and half of them had germinated on the seventh day; Melon did not germinate during 60 days; a quarter of the Nigella seeds germinated the ninth day; Sesamum germinated abundantly at the close of the ninth day; Sinapis germinated after 13 days (in a second experiment it germinated in about 40 hours, the average is 41 hours under a temperature of 12.9° C.); Iberis germinated in 3 to 4 days; Trifolium seeds sprouted unequally at the end of the third day (a second experiment gave 3 hours less than 3 days, or 69 hours, under a temperature of 13°).

(H) TEMPERATURES OF ABOUT 17° c.

Lepidium (mean of two experiments) germinated in 14 days, under 17.05°; Linum, mean of 2 experiments, germinated in 3 days, temperature 17.05° C.; Trifolium, 2 experiments, germinated in 2.6 days, temperature 17.05° C.; Sinapas, mean of 3 experiments, germinated in 1.7 days, temperature 17.2°; Collomia, 1 experiment, under 16.9° germinated in 5 days; Mays, 1 experiment, germinated in 33 days, temperature 16.9° C.; Melon, 1 experiment, began to germinate in 9 days, temperature 16.9°; Nigella, 1 experiment, germinated the sixth day, temperature 16.9°; Sesamum, 1 experiment, germinated the third day, temperature 16.9°; Iberis, 1 experiment, germinated the fourth day, temperature 16.9°.

(1) TEMPERATURES OF ABOUT 20° TO 21° c.

Lepidium germinated in 38 hours under 21.1°; Linum germinated in 36 hours under 21.1°; Mays began to germinate in 42 hours under 21.1°; Nigella germinated in 44 days under 21.1°; Sesamum germinated in about 33 hours under 21.1°; Sinapis germinated in 22 hours on the average under 21.1°; some Trifolium seeds germinated in 42 hours under 21.1°; Iberis germinated in 23 days under 20.4°; only one Collomia seed germinated in 15 days under 19.6°; 2 Melon seeds out of 10 germinated in 68 hours under 19.4°.

(K) TEMPERATURES FROM 24° To 25° C.

Linum germinated in 38 hours under 25.05°; Mays, i seed in 12 germinated in 23 hours (half the seeds had germinated within 44 hours under 25.05°); Melon, 2 seeds in 10 germinated in 44 hours, the others subsequently under 25.05°; Sesamum germinated in from 21 to 221 hours under 25.05° (a second experiment gave 22 hours under 24.6°); Sinapis germinated in about 36 hours under 25.05°; Trifolium germinated in 42 hours under 25.05°; Nigella and Iberis observations accidentally lost; Lepidium, 2 seeds in 10 germinated at the end of the sixth day, and the majority of the seeds between the sixth and seventh day under a mean temperature of 23.65°. A repetition gave 38 or 39 hours under a temperature of 21.1°; a third repetition gave 16 hours under a temperature of 26.5°, but which unfortunately ran up to 43° during a few hours. De Candolle concludes that there was some accident or mistake as to the first experiment, and therefore rejects it; probably the wrong seed was sown. He adopts for Lepidium 38 hours under 21.1° C. Collomia did not germinate until the twenty-seventh day, when 2 seeds sprouted under an average temperature of 21.5°.

(L) TEMPERATURES OF ABOUT 28° c.

Two Lepidium seeds germinated in 39 hours, but the greater part not at all in 4 days; Linum, 1 seed germinated at the end of 24 days, 3 seeds by the end of the third day, but the majority not at all; Mays, 1 seed germinated in 36 hours, and the majority, with vigor, in 48 hours; Melon, 1 seed germinated at the end of the third day, and the majority in 3 days; Sesamum germination began in 22 hours, and began to be abundant in 25 or 26 hours (a repetition gave 1 seed germinated in 31 hours under a temperature of 27.5° C.); Sinapis, 2 seeds out of 10 germinated at the end of the third day, a third seed 6 hours later, and the rest did not germinate; a few Trifolium seeds germinated at the end of the third day; Collomia and Nigella did not germinate in 8 days; a few Trifolium and Linum seeds germinated in 8 days under a temperature of 34°.

(M) TEMPERATURES FROM 40° тo 41° c.

Two Sesamum seeds germinated in 10 hours under 40.7°, and the cthers immediately after; 3 Melon 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 preceding 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 small tables:

Tables showing results of De Candolle's experiments on the germination of seeds at different temperatures.

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De Candolle's general conclusions are as follows:

(1) Contrary to the opinions of early investigators, such as De Seynes (1863) and Edwards and Colin (1834), it is now proven that some seeds, and probably others, do germinate in water at the temperature of 0° C.

(2) There is a minimum temperature at which each species germinates. These temperatures are as follows:

Sinapis alba germinates at 0° C., and possibly below this temperature if the water can be kept liquid.

2667-05 M- -3

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