146 Shaw—Structure of the Flowers in 
that the aérial cleistogamic flowers are developed among the 
green foliage, fairly sets aside also any question of their being 
a contrivance for protection against herbivorous animals. 
There is one fact in connection with cleistogamic flowers in 
general, which it does not seem to the writer has been prop- 
erly taken into account in theories concerning such. I refer 
to the rapidity with which the seeds are matured from them. 
In Polygala polygama, much less time is required to produce 
seed from the cleistogamic flowers, than for the maturing of 
seed from the evident flowers. The same is true of other 
plants. In Amphicarpea, for instance, the development of 
fruit from the cleistogamic flowers is relatively rapid. Some 
reason must lie back of this phenomenon. It would seem that 
a cleistogamic flower, requiring a minimum expenditure of 
material, leaves the shoot prepared to furnish the food very 
rapidly for the maturing of fruit. Here, as in many other 
points, Darwin’s suggestion after the lapse of years proves the 
soundest. Cleistogamic flowers are economical in the amount 
of food required to form the flower parts, and especially in 
the production of pollen. 
Although the observations of Hansgirg, Kerner and 
Schively leave no room to doubt that light has an influence 
on the development of the conspicuous parts of blossoms, 
and even a determining influence on the nature of the flower, 
as Vochting demonstrated in Lzvaria spuria, yet these leave 
the explanation of cleistogamic flowers still incomplete. 
Some other cause or purpose must exist for the habitual 
development, under favorable conditions of such numbers of 
aérial cleistogamic flowers as are put forth by Polygala 
polygama in the sunny weeks of summer. 
Considering the rapidity with which the fruits are matured, 
it seems to the writer that the explanation is chiefly to be 
found in the relation of cleistogamic flowers to the chas- 
mogamic ones in the matter of food supply. 
