Vol. VII July 1907 No. 3 



University Studies 



Published by the University of Nebraska 



COMMITTEE OF PUBLICATION 



C. E. BESSEY H. ALICE HOWELL 



T. L. BOLTON W. K. JEWETT 



F. M. FLING L. A. SHERMAN 



W. G. L. TAYLOR 



CONTENTS 



I Morphological Variation and its Causes ^ 

 IN Amblystoma tigrinum 



/. H. Powers . . . .197 



LINCOLN NKBRASKA 



Entered at the post-office in lyincoln, Nebraska, as second-class matter, as University 

 Bulletin, Series XII. No. 20 



