140 Shaw—Structure of the Flowers in 
Nectary.—No indication of a nectary has been observed in 
the cleistogamic flowers. 
In &. paucifolia no intermediate types of flower have as yet 
been found. It is possible, however, that a more extensive 
search in its native habitat would reveal the existence of such. 
Such studies as these must inevitably raise the inquiry, 
‘Why are cleistogamic flowers developed, and what purpose 
do they serve in the history of the plant?” Many investiga- 
tors have studied cleistogamic flowers and several explanations 
have been offered. : 
The existence of minute, self-fertilized flowers has been 
known for several centuries. The first satisfactory descrip- 
tion of them was given in 1857 by Dr. Miller, of Upsala,} 
who described the apetalous flowers of Viola canina. In 
1863 Hugo von Mohl? published further observations with 
the history of the subject. In 1867 Dr. Kuhn? gave to such 
flowers the fitting term “ cleistogamic.”’ 
We may now review the various opinions which have been 
held concerning the cause and meaning of these. 
Delpino* believed that cleistogamic flowers have been 
developed in order to ensure the production of seeds under 
climatic or other conditions, which tend to prevent the fertili- 
zation of the perfect flowers. Axell*® supposed similarly that 
the existence of cleistogamic flowers was due partly to low 
temperature, which hindered the development of ordinary 
flowers, and partly to failure of insects which, under normal 
circumstances, effect cross fertilization. Fritz Miller, in much 
the same way, believed that cleistogamy was to preserve the 
! Botanische Zeitung, 1857, p. 730. 
* Jbid., 1863, pp. 307-28. 
3 [bid., 1867, p. 65. 
«Sulla Opera la Distribuzione dei Sessi nelle Plante,’’ 1867, p. 30. 
5 «« Severin Axell,’’? Om an ordningarna for fanerogama vaxternas befrukting. 
Stockholm, 1869. 
