242 
Journal of Agricultural Research voi. xxvii, no. 
Obermayer (9), in Germany, reports that the most active blooming 
occurs in the early morning from before 7 a. m. to 11 a. m., followed by 
a marked decrease after 11 a. m., and reaching the lowest point between 
I and 3 p. m. From 3 to about 7 p. m. blooming again increases, but 
reaches only about 60 per cent of the intensity of that between 7 and 
II a. m. 
Percival (10. p. 122-129), at Reading, England, observed intense 
blooming periods between 5 and 7 a. m., 9 and 10 a. m., 2 and 3 p. m., 
and 8 and 9 p. m. Shitkowa ( 13 ), at Saratov, Russia, noted two active 
blooming periods at 5 to 7 a. m. and 5 to 6 p. m. Leighty and Hutche¬ 
son (<?), at two different places in lie United States, observed two 
intense blooming periods, one from 7 to 9 a. m. and another in the 
middle of the afternoon. 
The minimum temperature recorded during the whole experiment was 
55 0 F., while the maximum temperature was 78° F. The lowest tem¬ 
perature at which blooming occurred was 56° F.; the highest, 78° F. 
Godron (3) states that blooming begins at 4.30 a. m. when the temper¬ 
ature is not below 16 0 C. Frviwirth (2) says that blooming begins at 
4.30 a. m. when the temperature is above 14 0 C. Rimpau ( 11 ) and 
Koernicke (7) found the minimum temperature at which flowers bloom 
to be 12 0 and 13 0 C., respectively. Obermayer (9) observed blooming 
in a single strain of wheat toward 6 a. m. at 14 0 C. in a thick mist and 
toward 7 a. m. at 15 0 C. in a mist and dropping rain. 
Of all the flowers which bloomed on six of the heads under observation 
80.2 per cent set seed, as is shown in Table VIII. The seventh head was 
destroyed by birds before harvest. The percentage of flowers setting 
seed in the four different positions in the spikelet, is largest for the first 
or lowest position, nearly all of these flowers producing kernels. The 
percentage decreases from the lowest to the highest position, little 
difference existing, however, between those in the first and second 
positions. 
ADDITIONAL OBSERVATIONS 
The following observations were made separately from those reported 
in the preceding part of this paper: (1) Wheat heads on plants grown 
in the field, which were completely submerged in water from several 
days before blooming until complete maturity of the heads, were found 
to open their flowers apparently in the same manner as under normal, 
unaltered conditions, with the exception that the filaments did not 
elongate nor did the anthers dehisce. Flowers under these circumstances 
remained open for several days. 
(2) Plants were placed in a light-tight (dark) room at a temperature 
between 6o° to 70° F. for one week at the time of blooming. The flowers 
on the heads bloomed completely under these conditions in approximately 
the same length of time as under normal conditions. Flowers were 
observed with glumes as widely separated in the dark as in the daylight, 
under favorable temperature conditions. 
(3) In a greenhouse at a temperature of 55°t0 56°F. flowers were 
observed with their glumes separated 3 mm. (The greatest separation 
under normal conditions was found previously to be 4 mm.) Movement 
of the anthers was easily observed at this temperature. VHien the tem¬ 
perature was gradually lowered, extension of the filament was retarded, 
so that at a temperature below 55 0 F. no perceptible further movement 
