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1 



=! The Journal of Experimental Zoology. != 



Edited by: William E. Castle, Harvard University; Edwiu G. Conklin, Prin- 

 ceton University; Charles B. Davenport, The Carnegie Institution; 

 Horace Jaj^ne, The Wistar Institute; Herbert S. Jennings, Johns Hop- 

 kins University; Frank R. Lillie, University of Chicago; Jacques Loeb, 

 University of California; Thomas H. Morgan, Columbia University; 

 George H. Parker, Harvard University; Charles O. Whitman, Univer- 

 sity of Chicago; Edmund B. Wilson, Columbia University; Ross G. 

 Harrison, Managing Editor, Yale University. 



Contents of Part 1, Vol. 6. January 1909. 



Springer, Ada, A Study of Growth in the Salamander, Diemyctyles viridescens. 

 Wilson, Edmund B., Studies on Chromosomes. IV. The "Accessory" Chromosome 



in Syromastes and Pyrrochoris with a Comparative Review of the Types of 



Sexual Differences of the Chromosome Groups (with two plates and two text 



figures). 

 Stevens, N. M., Further Studies on the Chromosomes of the Coleoptera (with four 



plates). 

 Stevens, N. M., An Unpaired Hétérochromosome in the Aphids (with two plates). 

 Whitney, David Day, The Effect of a Centrifugal Force upon the Development and 



Sex of Parthenogenetio Eggs of Hydatina Senta (with one plate). 

 Whitney, David Day, Observations on the Maturation Stages of Parthenogenetio 



and Sexual Eggs of Hydatina Senta (with five text figures). 



The Journal of Experimental Zoology is published quarterly. Sub- 

 scriptions to Volume 6, Five Dollars (Foreign ^ 5.50) postpaid. 



L 



The Wistar Institute of Anatomy and Biology, 

 Philadelphia, Pa., Ü. S. A. 



J 



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-% Berh'n, Hamburg, Wien, London, Paris, St. Petersburg, Moskau, New-York. ^7 Gegründet 1756. 



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