PURSLANE FAMILY 79 
blossom to plunder it of pollen and nectar, but on 
account of the closed stigmas they cannot fertilize 
the ovaries of the pistil, either with the pollen of 
the same or that from another flower. On the 
second day the filaments have bent outward in 
such a way as to press the anthers against the 
petals, and thus to keep them away from the stig- 
‘mas which have now opened. If at this time the 
flower is visited by a bee more or less covered 
with pollen from another plant, some of the 
pollen-grains will pretty surely be brushed upon 
the stigmatic surface, and in consequence cross- 
fertilization will result. The statement has fre- 
quently been made that the closing of the petals 
must bring about self-fertilization, but this in 
general is not the case. Mr. Charles Robertson, 
who has studied with his usual care the pollina- 
tion of the Virginia Spring Beauty, has said: 
“Tf self-fertilization by closing of the flower 
occurs, it is after the anthers have been exposed 
to insects for two days and the stigma for one, 
but many flowers which I marked exposed their 
stigmas again on the third day, showing that 
fertilization of any kind had failed on the day 
before.” My own observations on the Carolina 
Spring Beauty indicate a similar behavior of the 
flowers of this species. 
The blossoms of the Spring Beauty are visited 
by an extraordinary number and variety of in- 
