INTRODUCTORY NOTE J 



at that time Instructor in Entomology, was associated with the present 

 writer in all of the silkworm work, and fully deserves therefore the title 

 of collaborator. Certain data also have been obtained from the careful 

 and extensive studies of Instructor McCracken, who has given special 

 attention during the last three years to the inheritance of the moricaud 

 larval sport and to the behavior of bivoltinism as a heritable character. 

 I am indebted to Professor E. Verson, director of the royal silk 

 culture station at Padua, Italy, to Mr. S. I. Kuwana, entomologist of 

 the imperial agricultural station at Nishigahara, Tokyo, Japan, and to 

 others, for eggs of various races. Dr. L. O. Howard, Chief of the 

 Bureau of Entomology of the U. S. Dept. of Agriculture, helped out the 

 work in one of the years by an appropriation for assistance. Mrs. 

 Carrie Williams and Miss E. L. Story of San Diego, California, ren- 

 dered very efficient and faithful help in the 1907 rearings. Drawings 

 for the present paper were made by Mary Wellman and Maud 

 Lanktree as indicated on the respective plates. To all of these, and 

 to numerous helpers, especially Isabel McCracken and R. W. Doane, 

 in the arduous and exacting labor of rearing, observing, and tabulating 

 through the past six years, the writer expresses his obligation and 

 gives his sincere thanks. 



