150 Retrograde Varieties 



But the diversity of the color patterns is far 

 from being exhausted with these simple in- 

 stances. Apart from them, or joined to them, 

 other complications are frequently seen, which 

 it is impossible to analyze in such an artificial 

 way. Here we have to return to our former 

 principle, the comparison of different varieties. 

 Assuming that single units may be lost, ir- 

 respective of the others, we may expect to find 

 them segregated b}^ variation, wherever a suffi- 

 ciently wide range of color-varieties is in culti- 

 vation. In fact, in most cases a high degree of 

 dissimilarity may be reached in the simplest 

 way by such a separation of the components, 

 and by their combination into most diverse 

 smaller groups. A very nice instance of such 

 an analysis of flower-colors is afforded by the 

 ordinary snapdragon. The beautiful brown- 

 red color of this common garden-plant is com- 

 posed on one side of yellow elements, on the 

 other of red units. Of the vellow there are 

 two, one staining the whole corolla with a light 

 hue, as is to be seen in the pure yellow variety 

 called luteum. This form has been produced 

 by the loss of the whole group of the red con- 

 stituents. If the yellow tinge is also lost, there 

 arises a white variety, but this is not absolutely 

 colorless, but shows the other yellow constit- 

 uent. This last stains only some small parts 



