No. 4o1.] THE FRUITING OF THE BLUE FLAG. 373 
threads of fungus, there appeared fungus gnats (Scatopse puli- 
caria Loew.) in great numbers. It is quite probable that the 
ortalids attacking the fresh buds, the pomace flies coming 
when the saccharine juices of the flower first begin to ferment, 
the other flies and beetles clearing up the rotting débris, with 
a few parasites to hold the commonest in check, form an entirely 
natural succession of forms belonging with such conditions. 
IV. FERTILIZATION. 
Not wishing to leave actual fertilization out of account, I (1) 
_ pollinated by hand a large number of flowers and marked them 
for examination later, and (2) counted the fertile and abortive 
ovules in a large number of capsules developing from flowers 
fertilized by insects. In my hand-pollination experiment half 
the flowers were treated with their own pollen, half with pollen 
from other plants. Before the seeds had grown sufficiently to 
be distinguished with certainty from the abortive ovules, grass- 
hoppers and Mamestra larvae had eaten all but a few. Those 
that remained happened to be half self-pollinated, half cross- 
pollinated, and the result may be worth mentioning, even 
though they were but few. The average by capsules was as 
follows : 
Cross-pollinated, ovules, 79; fertilized, 74, unfertilized, 5 (for 2 capsules). 
Self “ “ 82; ‘ 16, Im ( “ 2 “ : 
These were small capsules, from flags growing among thick 
sedges. i 
In a flourishing flag clump growing in the edge of a wood- 
land pool I selected thirty well-developed capsules from flowers 
fertilized by insects, for the following tabulation. The position 
of the several capsules in the cluster is indicated by the letter- 
ing in the first column, which is the same as that of Fig. 4. 
