740 Fluctuations 



tigation of true double races, or ever-sporting 

 varieties. The striped snapdragon shows a 

 curve of its stripes with two summits, one cor- 

 responding to the average striped flowers, and 

 the other to the pure red ones. Such cases may 

 be discovered by means of curves, but the con- 

 stituents cannot be separated by culture-exper- 

 iments. 



A curious peculiarity is afforded by half- 

 curves. The number of petals is often seen 

 to vary only in one direction from what should 

 be expected to be the mean condition. With 

 buttercups and brambles and many others there 

 is only an increase above the typical five; 

 quaternate flowers are wanting or at least are 

 very rare. With weigelias and many others the 

 number of the tips of the corolla varies down- 

 wards, going from five to four and three. Hun- 

 dreds of flowers show the typical five, and de- 

 termine the summit of the curve. This drops 

 down on one side only, indicating unilateral 

 variability, which in many cases is due to a 

 very intimate connection of a concealed sec- 

 ondary summit and the main one. In the 

 case of the bulbous buttercup, Ranunculus bul- 

 bosus, I have succeeded in isolating this second- 

 ary summit, although not in a separate variety, 

 but only in a form corresponding to the type 

 of the ever-sporting varieties. 



