VARIATION IN NUMBER OF SEEDS 



351 



native country. In judging Bumpus 's data on the directly 

 measurable characters by the standard deviation instead 

 of the range of variation Pearson 3 concluded that the 

 American egg is not more variable than the English but 

 rather less so when a more representative English series 

 is taken. It is quite impossible to determine from the 

 color and shape appreciations whether Pearson's English 

 or Bumpus 's American series is the more variable, but it 

 seems to me upon rereading Bumpus 's paper that he 

 makes a very good case for a greater variability in color 

 and shape of the eggs of his American as compared with 

 his English series. However, Pearson's suggestion of a 

 possible change in the color of the egg must be remem- 

 bered. Vernon 4 considers the American eggs more vari- 

 able in shape and color. 



Bumpus 's second attempt to secure data upon this 

 question was with the introduced Littorina. 5 He found 

 from an examination of three English and ten American 

 series, each of about one thousand individuals, that the 

 American shells are much more variable than those from 

 the British Isles. Duncker 6 who has reworked the data to 

 express the variability in terms of the standard deviation 

 and theoretical instead of empirical range agrees with 

 his conclusions. 



The results reviewed above indicate that more data on 

 this question are much needed. Although his conclusions 

 were based upon somewhat unsatisfactory statistical 

 methods Professor Bumpus deserves very large credit for 

 his thoroughly pioneer attempts to solve some of the 

 problems of evolution in the only way in which they can 

 be solved— by the collection of pertinent quantitative 

 data. The problem of variation is such a complex one 



'Pearson, K., "Variation in the Egg of the Sparrow," Biometrika, 1, 

 247-249, 1901. 



♦Vernon, H. M., "Variation in Animals and Plants," New York, 1903. 



5 Bumpus, H. C, "The Variations and Mutations of the Introduced 

 Littorina," Zool. Bull, 1, 247-259, 1898. 



•Duncker, G., "Bemerkung zu dem Aufsatz von H. C. Bumpus: The 

 Variations and Mutations of the Introduced Littorina," Biol. Centralbl., 

 18. 569-573, 1898. 



