Polygala polygama and P. paucifiora. 143 
different from others which bear cleistogamic flowers, or that 
all these are merely teratological cases? Hansgirg’ dwells 
on the importance of light and other factors in determining 
the development of blossoms, and states that flowers may 
be rendered potentially cleistogamic in several ways. Such a 
condition he calls pseudocleistogamy and distinguishes varie- 
ties according to the character. Kerner’ regards cleistogamy 
as due primarily to lack of light. ‘“ This result throws some 
light on the nature of the stimulus which causes the forma- 
tion of the flowers in question. No open, aérial flowers were 
produced by Viola sepincola so long as it grew in the cool 
shade of a dense wood, but when transferred to open ground, 
accessible to sunlight, such flowers were developed. One can 
hardly err in ascribing to the sun’s rays a very important influ- 
ence in stimulating plants to the inception of flowering shoots, 
especially such as bear blossoms possessing bright colored 
petals. Indirectly, however, this advantage accrues to the 
plants in question that, living as they do in the deep shade, 
where no bees would, in any case visit them, even if they had 
open flowers, they can confine their constructive energy to the 
inception and development of cleistogamous flowers and save 
themselves the trouble of producing open flowers adapted to 
cross-pollination, but useless in the place in question. If the 
spot where the violet grows becomes exposed to the sunlight 
through the trees shading it being blown down or felled, 
humble and hive-bees make their appearance in search of 
honey, and, buzzing from flower to flower, cross the flowers 
one with another. In such circumstances the open, sweet- 
scented violet blossoms are in request, and the same plant 
individual, which for years in the dark shade has developed 
none but cleistogamic flowers, is now stimulated by the sun’s 
rays into producing flowers with expanded petals. 
1Hansgirg. Bot. Central, 45, p. 74. 
2Natural Hist. of Plants, II, p. 395. 
