NOVEMBEE 16, 1906.] 



SCIENCE. 



628 



in Fig. 1, where A represents the condition 

 accepted by the systematists as typical of the 

 species (both right and left elytra are shown) ; 

 B shows the two spots of the middle trans- 

 verse pair of the left wing-cover fused; G, 

 the corresponding two spots of the right wing- 

 cover fused; D^ the two spots of the posterior 

 transverse pair of the left wing-cover fused; 

 E, the corresponding spots of the right wing- 

 eover fused; F, the longitudinal fusing of the 

 spots on the left wing-cover, and G, the cor- 

 responding condition for the right wing cover. 

 These different patterns are closely con- 

 nected by intergrading conditions; that is, 

 there may be (theoretically) and are (actu- 

 ally) all degrees of fusion of the two spots in 



Fig. 1. Diagrammatic representation of the 

 varying elytral color pattern of the California 

 flower beetle, Diabrotica soror. 



these various pairs that show fusion at all, 

 from the slightest running together to the 

 complete type shown by the diagrams of Fig, 1. 

 But for the sake of aggregating individuals 

 into describable groups any fusion is called 

 fusion, and the existence of even the slightest 

 space or line of green between two spots is 

 recognized as ' no fusion ' or ' free spots.' As 

 a matter of fact, in the great majority (about 

 five sixths) of cases of fusion the spots are 

 well joined. 



In the following tabulations and graphic 

 representations (by frequency polygons) of 

 the condition of the varying color pattern in 

 the species (on the Stanford University 



campus) in different years, series of approxi- 

 mately 1,000 are used. That a series of 1,000 

 individuals collected from one locality at one 

 time fairly represents, in the variation re- 

 vealed by its members, the actual variation 

 conditions of the species in this locality, as 

 regards both kinds of variation and frequency 

 of these kinds, is proved by repeated tests 

 made by examining and tabulating successive 



Fig. 2. Frequency polygon of the variation in 

 elytral pattern of 905 specimens of the California 

 flower beetle, Diabrotica soror, collected on the 

 Stanford University campus, 1895. 



thousands and finding a practical identity in 

 these separate series. Indeed, series of 500 

 gave practically always approximately the 

 same curve as those of 1,000. But the larger 

 number is the safer. 



Attending now to the actual variability 

 shown by the elytral color-pattern of Diabro- 

 tica soror in the various series examined (in 

 the years 1895, 1901, 1902, 1904 and 1905), 

 we find the species in 1895 showing (Fig. 2; 



