REACTIONS OF STAMENS TO SHOCK 



19 



Fig. 6. Sections of two flowers of Opunlia. 

 e, with stamens in normal position, d, with sta- 

 mens bending toward the style in response to 

 shock of rough objector insect. After Tourney. 



Strike the terminal leaflets of a normal specimen of Biophytum 

 so lightly that no reaction ensues and repeat at intervals to de- 

 termine the memory, or time during which the stimulus-effects are 

 retained and cumulated, finally producing full excitation. 



26. Reactions of Stamens 

 of Opuntia to Shock. The 

 flower of Opuntia contains 

 a single central style sur- 

 rounded by a number of 

 shorter stamens. Bees or 

 other insects entering the 

 flower in quest of honey 

 pass down the style, touch- 

 ing the filaments of the sta- 

 mens. As a result of such 

 stimulation the stamens 

 curve inwardly toward the 

 style, forming an arched cage with the style in the center, in 

 which the bee is imprisoned. In brushing aside the 

 anthers to escape the bee carries away some of the 

 pollen, which may be left in another flower, effect- 

 ing cross pollination. The curvature of the 

 filaments is so rigid that the bee may be held for 

 several minutes, and its struggles act as repeated 

 stimuli, causing tetanus of the filaments. After a 

 time, however, the organs become accustomed to 

 the repetition of the stimuli, the tetanus is relaxed 

 and the filaments straighten out to their original po- 

 sition, allowing the insect to escape. If it is not 

 irritation of the possible to observe this action, imitate the behavior 

 stigmatk sur- f the bee with a small wire or wooden splinter. l 



Similarly sensitive stamens may be found in 

 Mammillaria, Echinocactus, Echinocereus and other 

 reactions may be seen in Berberis, and in some of the Cichoria- 



'Touiney, J. W. Sensitive stamens in the genus Opuntia. Asa Gray Bull. 7 : 

 35- l8 99- 



Fig. 7. Pis- 

 til of Mimulus. 

 b, expanded po- 

 sition, a, after 



faces. 

 Belzung. 



After 



