I20 BIOMETRY 
as are very seldom made use of by systematists for 
the distinction of natural species. 
BIBLIOGRAPHY. 
Gatton, F.: Natural Inheritance, 1889. 
Pearson, K.: The Grammar of Science, second edition, 1900. 
Vernon, H. M.: Variation in Animals and Plants, 1903. 
Davenport, C. B. : Statistical Methods, Igo4. 
BIOMETRIKA, 190I— 
JoHaNnnsEeNn, W.: Ueber Erblichkeit in Populationen und in 
reinen Linien, 1903. 
Elemente der Exakten Erblichkeitslehre, 
1909. 
