Stability and Real Atavism 173 



tendencies of the pale blue flag or Iris pallida. 

 The flowers of the blue flags have a perianth 

 of six segments united below into a tube. The 

 three outer parts are dilated, and spreading, or 

 reflexed, while the three inner usually stand 

 erect, but in most species are broad and colored 

 like the outer ones. Corresponding to the outer 

 perianth-segments are the three stamens and 

 the three petal-like divisions of the style, each 

 bearing a transverse stigma immediately above 

 the anther. They are pollinated by humble-bees, 

 and in some instances by flies of the genus 

 Rhingia, which search for the honey, brush the 

 pollen out of the anthers and afterwards de- 

 posit it on the stigma. According to systematic 

 views of the monocotyledons the original proto- 

 type of the genus Iris must have had a whorl of 

 six equal, or nearly equal, perianth-segments 

 and six stamens, such as are now seen in the 

 more primitive types of the family of the lilies, 

 as for instance in the lilies themselves, the 

 tulips, hyacinths and others. As to the 

 perianth this view is supported by the 

 existence of one species, the Iris falcifolia, 

 the perianth of which consists of six equal 

 parts. But species with six stamens are 

 wholly lacking. Heinricher however, in culti- 

 vating some anomalous forms of Iris pallida, 

 succeeded in filling out this gap and in produc- 



