272 THE STRUCTURE OF FLOWERS. 



have become regularly autogamoas, while others are now 

 anemophilous, it may be due to the fact that, if a flower has 

 been entomophilous and even strongly protandrons, the first 

 stage of degradation is to bring the essential organs to a 

 homogamous state. If they stop there, and become autoga- 

 mous as well, whicb is the usual result, then the flower will 

 remain persistently self-fertilising, as, e.g., Shepherd's-purse, 

 Chickweed, Knot-grass, etc. 



If, however, the flower had been protogynous, such as 

 early-flowering HeHebores, Prunus communis or some Alpine 

 species, with " long-lived stigmas," then this protogyny, 

 associated with other degradations of the corolla, etc., which 

 only tend to increase it, has ended with anemophily. 



In the first case the androecium of protandrous flowers 

 has come down from its previous highly differentiated state, 

 so as to be homogamous with the stigmas. From the other 

 or protogynous condition, the gyncecium has not been brought 

 back again so as to be homogamous with the anthers and 

 pollen, butj on the contrary, it may have become even 

 further differentiated, and so has now no fertiliser to depend 

 upon except the wind, 



