XOTES OX THE IRRITABILITY OF THE STIGMA. 



209 



althoLio-li I am as yet unable to detect any decided structural 

 pecLiliarity. 



The folli^wiiig observations were mnde to ascertain the signifi- 

 cance of the movement and to know in what relations, if any, it stands 

 with respect to the visits of insects. 



April 16, 17. Rainy. I visited certain spots wliere the 

 plants were abundant. Many flowers were open. I saw no single 

 insect near, and the stigmatic lobes of almost all the flowers were 

 deflexed. 



April 18. Clear warm day ; 22°C. at noon. At one o'clock 

 p. M. I went to the same places and found that many of the 

 flowers had their stigmas closed. Soon I saw two or three bees 

 come with a buzzing note. They alighted on some of the flowers, 

 thrusted their mouth-parts deep into the throat of the corolla 

 which had honey stored in the basal part of the lower lip. In so 

 doing the heads of the insects unavoidably struck against the open 

 lobes of the stigma wdiich at once closed. The heads were then 

 thrust in deeper and came in contact with the anthers. In a few 

 minutes thev visited no less than a liundred flowers and then 

 flew away. 



At 3 p. M. On the same day I revisited the same places 

 and found a similar occurrence. 



At 6 p. M. Comparatively small number of flowers (about 

 one-third) had their stigmas closed ; no insects were flying about. 



At 9 p. M. Dark night. The flowers did not close, and the 

 stigmas were wide open. 



April 19. Foggy morning. At 7 a. m. I saw the stigmatic 

 lobes cpiite re flexed. 



At 9 A. M. A few insects were found entering the flowers. 

 April 20. Clear but very windy day. At noon I visited 



