MOVEMENTS OF STIGMAS AND STAMENS 391 



§ 14. Self-Sterility 



The most perfect means of preventing autogamy in a 

 hermaphrodite flower is self-sterility. This seems to be a 



Fig. 60. — Cistus salvifolius ; i , flower from above ; 2, section through 

 flower, stamens in normal position; 3, stamens after stimulation, i 

 nat. size, 2 and 3 X 2-5. (After Knoll.) 



not uncommon phenomenon, though much carefully con- 

 trolled work must be done before we can have a true idea 

 of its frequency. Knuth states that in most cases there is 



