114 
AMERICAN JOURNAL OF BOTANY 
[Vol. 9, 
were then open. As a control for the last preparation, 9 stigmas were 
pollinated and closed. The Catalpa flowers for this test were plucked at 
the same time as the preceding set that were given starch, and the two 
groups were carried on side by side. At the end of 75 minutes and of 135 
minutes, 8 were open and one closed. Five and one quarter hours after 
pollination and the primary closing, 5 were closed and 4 open. After 16 
hours from the beginning, 6 were closed and 3 were open. 
In the preceding section, Tecoma was found to keep its stigmas closed 
when given wheat flour. A test with starch only, using two stigmas in 
flowers in the house, showed the starch keeping the stigmas closed for 23 
hours, when observations were discontinued. 
Emery powder. Very fine emery powder was washed in strong alcohol 
and later in several changes of water, and then dried. Large amounts of 
this powder were placed in the angle of the divergent lobes of eight stigmas 
of Tecoma radicans. The flowers bearing these stigmas were brought into 
the laboratory at noon, and set in beakers with their lower ends in water. 
The emery powder was applied at 1 130 P.M. and the stigmas were immedi- 
ately closed. At the same time six stigmas of flowers similarly treated 
were given wheat flour and closed. Observation was not made for four 
and one half hours, when all stigmas given emery powder were open, and 
all given flour were closed. 
3. Living and dead pollen, enzymes, proteins. The foregoing results ob- 
tained with Tecoma, in the behavior of stigmas when applying emery 
powder compared with the behavior when applying wheat starch, and with 
Catalpa when using wheat flour compared with the behavior when using 
pollen, show that the flour exerts an influence not possessed by the emery 
powder, and the pollen exerts an influence not possessed by the flour. 
Other results have shown with Catalpa that wheat flour exerts a closing 
efl"ect to a greater degree than the flour deprived of its protein. In attempt- 
ing to solve some of the questions arising from these relations, one may 
assume that it is either the proteins or the enzymes in flour that make it 
more effective than starch, and that it is either the enzymes or the germina- 
tion effects of pollen that make pollen more effective than flour and starch 
in inducing permanent closure of the stigmas. 
To determine the difference in behavior of stigmas with living and with 
dead pollen, a quantity of pollen from recently opened anthers of Catalpa 
was covered with water at 88° C. The water was decanted and the pollen 
grains were washed in water and dried at 60°. The pollen was then placed 
on 12 stigmas of flowers standing in water in the house, and the stigmas 
closed. The weather was warm and moist. Eleven of the stigmas opened 
within an hour. In three hours all were open. Seventeen hours after 
applying the pollen, all stigmas were still open. There were no controls 
made at the same time as the foregoing tests, but the day before, under 
similar conditions, four stigmas of Catalpa were given living pollen and 
