THE PHILIPPINE 
Journal of Science 
C. Botany 
VOL. VIII 
JULY, 1913 
No. 4 
THE PHENOMENON OF FATIGUE IN THE STIGMA OF MARTYNIA 
By William H. Brown 
{From the Botanical Section of the Biological Laboratory, Bureau of Science, 
Manila, P. I.) 
The plants upon which the present observations were made 
were grown in the greenhouse of the department of botany 
of the Michigan Agricultural College during the spring of 1911. 
Here the plants were much smaller than in the garden during 
the summer months, but the flowers in the two cases appeared 
to be identical. 
The single stigma of Martynia prohoscidm Glox. terminates 
in two, thin, recurved lips. Shortly after the opening of the 
flower these two lips become sensitive to mechanical stimulation, 
and may be made to close together by applying to one of them 
a blow of sufficient force to cause it to bend. The process of 
closing requires only a few seconds. If the stigmas have not 
been pollinated the two lips will again spread apart and assume 
their original position and frequently in less than three minutes. 
When the stigmas are pollinated and the two lips then brought 
together as the result of mechanical stimulation, they will usually 
spread apart slightly in from ten minutes to an hour, after which 
they again close and remain so until they wither. It would 
seem that this closing together of the lips furnishes the pollen 
with excellent conditions for germination. 
When pollen from tomato or squash plants was applied to the 
lips before they were brought together by mechanical stimula- 
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