1921] GARDNER—GERMINATION 261 
alternating temperature cultures were frozen on the morning of 
February 26. On this date observations were made and the cultures 
placed in light at room temperature to test viability. 
As shown in table VII, the constant high temperature effectively 
inhibited the germination of all seeds except those of Verbascum 
Thapsus. The subsequent incubation in light at room temperature 
showed fatal injury to the embryos of Daucus Carota, Oenothera 
biennis, and Nicotiana Tabacum. The constant low temperature 
delayed germination, but seemed to induce increased germination 
in light in seeds of Daucus Carota, Oenothera biennis, and Verbascum 
Thapsus. -This is especially noticeable in Oenothera biennis seeds. 
TABLE VII 
Fy deoeks AT Cee NS AT imgrevmcpaeny 4 c. . 
_|IN DARKNESS FOR ONTROL AT 
“@)axp int Lie a) anp — 17 DAYS 17 DAYS (a) AND | ROOM TEMPERA- 
S TEMPERA- THEN AT ROOM TURE FOR If 
po ae "Tune In Ligue | ‘TURE IN LIGHT gape nob — 
FOR 12 DAys (b) | For 12 Days (6) 12 pays (b) 
Gi | 2 be. | ee | OE 
Verbascum — ae 14 78 ° 86 6 76 
Rumex crispus.......... o 1 o | 58 Oo | 56° 82 | 30 
Daucus Carota.......... ° I ° 60 S.) 28 7.38 6 
Oen thera biennis....... ° 4 ° 64 ° go 4 2 
Nicotiana Tabacum...... ° ° ° 40 ° 26 58 2 
The alternating high and low temperature treatment delayed the 
germination in the same way as did constant low temperature. 
As shown by the subsequent incubation, Daucus Carota seeds were 
injured most. The germination of seeds of Nicotiana Tabacum 
and Rumex crispus was materially reduced by this treatment, while 
the germination of seeds of Verbascum Thapsus was favored, and 
the germination of seeds of Oenothera biennis very greatly increased. 
In a further effort to distinguish effects of light and temperature 
an experiment was carried out as follows. Seeds were counted 
into Petri dishes, having filter paper wetted with distilled water for 
substratum, and placed under the following conditions: set @ in 
light at 10°C. for 8 days and then at 25°C. for 8 days; set 0 in 
darkness at 10°C. for 8 days and then at 25°C. for 8 days; set ¢ 
