262 BOTANICAL GAZETTE [APRIL 
in light at 10° C. for 8 days and then in darkness at 25° C. for 8 days; 
set d in darkness at 10°C. for 8 days, then at 40° C. for 4 days, 
followed by 4 days at 25°C. At the end of the 16 days’ treatment 
all of the cultures were placed in light for 8 days at room tempera- 
ture. The experiment was begun July 24. 
Comparison of the data in a of table VIII with the control 
indicates that incubation in light at low temperature followed by 
incubation at room temperature results in reduction of percentage 
of germination of Daucus Carota seed. A comparison of a and 
the control indicates that alternating temperatures may in a 
measure replace light in the case of germination of Verbascum 
TABLE VIII 
J 
ss (a) (b) (c) (a) 
cae 
BOs Z 
° g GJ ¢ — 
eee ei to oP is Oe igele Pl. we 
zea lg [2 12 [2 [2 18 |b [Bsl sa [2 Mass 
SEEDS o me 15 13 |e 1S 18 fy | Sol = (3 Wi Sac3 
siege Same PERS HE Xn 2 S| An ao\" ERs 2S 2 SoS Blo 
_ a a Ge] oo we le | SS | te os) + wo} 
FA $2.2 ree) Avi Le i(oU Sian (= vile Ee 
2 ia a2 28 Hol 82 | Boo 12 | BO | B00 |4o0 8 gO 300 
= a ra c e Sul aU] ae | SO] 6% ee l@eulo to! au 
% = co] Peo | Peo IMS] Seq | 8S IS | 09 |U S/o oa] 3S 
8s), %) 3 a Ped | Poel cdl ake B= tesla teal” — ao 
A |All |e BS is |e ae (ee H |S |B fH 
VerbascumThapsus| 94 | 0 | o | 95 | 98 | o | 64 | 83 | 0] 71 | 71 | oO} 1 | 88 
Rumex crispus. 89} 2/0108} 08 |o] 2 °o |} 94 Oo} 31 Tae 
Daucus Carota.... 406) Y4) 35 O72 26 | or ar 7 a te. fs 
Oenothera biennis.| 85 | 0 | o | 69 | 69 | o | 16 | 16 | 0 2 21054 1 14 
NicotianaTabacum| 53 | 0 | 0 | 70 | 72/0] o| 310] 35|35|0] © I 
Thapsus seeds, that it is an important factor in the germination of 
Rumex crispus seeds, and further indicates the necessity of light 
in the early periods of incubation of Daucus Carota, Oenothera 
biennis, and Nicotiana Tabacum. A comparison of 6 with a points 
again to the necessity of light in Rumex crispus, Daucus Carota, 
Oenothera biennis, and Nicotiana Tabacum, and indicates that 
some inhibiting factor developed during the 8 days in darkness in 
the case of Oenothera biennis and Nicotiana Tabacum. A com- 
parison of c with the control indicates that light does its work on 
such seeds as Verbascum Thapsus, Rumex cris pus, and in a measure 
on Nicotiana Tabacum even at low temperature, and that as soon 
as heat is supplied germination occurs. Incubating Daucus Carota 
and Oenothera biennis seeds at low temperature for a period of 8 
