PKEFACE. 



THIS book has been issued iu answer to a repeated call for a 

 simple presentation of the newer statistical methods in their 

 application to biology. The immediate need which has called 

 it forth is that of a handbook containing the working formulae 

 for use at summer laboratories where material for variation - 

 study abounds. In order that the book should not be too 

 bulky the text has been condensed as much as is consistent 

 with clearness. 



This book was already in rough draft when the work of 

 Duncker appeared in Roux's Archiv. I have made much use 

 of Duncker's paper, especially in Chapter IV. I am indebted 

 to Dr. Frederick H. Safford, Assistant Professor of Mathe- 

 matics at the University of Cincinnati and formerly Instructor 

 at Harvard University, for kindly reading the proofs and for 

 valuable advice. To Messrs. Keuffel and Esser, of New York, 

 I am indebted for the use of the electrotypes of Figures 1 and 2. 

 Finally, I cannot fail to acknowledge the cordial cooperation 

 which the publishers have given in making the book ser- 

 viceable. 



C. B. DAVENPORT. 



BIOLOGICAL LABORATORY OF THE BROOKLYN INSTITUTE, 



COLD SPRING HARBOR, LONG ISLAND, 



June 29, 1899. 



iii 



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