AUTOGAMY BY COILING OF STAMKNS AND 1'ISTIL. 357 



brought in the process of involution into contact with the pollen of one or more 

 anthers. Most of the plants which exhibit this curious phenomenon have the 

 common property of being ephemeral, but they belong to most different families. 

 In a number of Commelynaceae Commelyna coelestis, for example (see fig. 301) 

 the stigma is situated in front of and lower than the anthers when the flower, 

 which faces sideways, is quite newly open (fig. 301 J ). Honey is secreted on curious 

 palmately-lobed nectaries, and if in this first period of the flower's developm 

 insects come in quest of the honey they make use of the anthers to alight on, and 

 in so doing besmear themselves with the pollen, which is already emerging through 

 the lateral sutures of dehiscence of the anthers. Soon afterwards the stamens 

 become spirally coiled, and the style, which meanwhile has grown to the same 

 length as the stamens, curves in such a manner as to bring the stigma to a some- 

 what higher position than it previously occupied, and to make it the most con- 



Fig. 301.-Autogamy by means o! spiral twiutings of stamens and style. 



venient place for insects to settle upon (fig. 301*). The arrival of insect, which 

 have visited younger flowers is at this stage sure to be accompany by era 

 tilization. This state of affairs, however, only lasts a very short time 

 then winds itself into a spiral, and becomes entangled with the coded stamens ,w 

 the inevitable result that the stigma comes into contact wrth one or other of 



j -^ llpn rficr 301 3 ^ The whole process occurs in 

 and ets covered with pollen (,ng. avi ;. 



lecessarv to observe that the flowers are protogynous, that the 



liar movements of the style and ^men^and^hat by W ^.^ 





