128 



THE AMERICAN NATURALIST 



[Vol. XLV 



rious symmetrical table; at the same time it involves much less 

 labor than the method given by Pearl. When there are many 

 tables to be computed, the amount of drudgery it saves is great. 



PAPERS CITED 



1909. Harris, J. A. A Short Method of Calculating the Coefficient of 

 Correlation in the Case of Integral Variates. Biometrika, 7, 215-218. 



1910. Harris, J. A. The Arithmetic of the Product Moment Method of 

 Calculating the Coefficient of Correlation. Amer. Naturalist, 44, 

 693-699. 



1907. Pearl, E. A Biometrical Study of Conjugation in Paramecium. 

 Biometrila, 5, 213-297. 



1901. Pearson, K. Mathematical Contributions to the Theory of Evolu- 

 tion— IX. On the Principle of Homotyposis and its Relation to 

 Heredity, to the Variability of the Individual -and to that of the 

 Race. Philos. Trans., A, 197, 285-379. 

 The Johns Hopkins University. 



H. S. Jennings. 



