122 T. H, MORGAN 



I wish to acknowledge my indebtedness to Mr. A. H. Sturtevant 

 and Mr. C. B. Bridges with whom I have discussed the theoretical 

 questions involved in the experiments, and also my indebted- 

 ness to Miss E. M. Wallace and to Mr. J. S. Dexter who have 

 made the greater part of the 55,000 records that furnish the 

 evidence on which the conclusions rest. 



