372 ORILLA STOTLER WERNER. 



PLATE 10. 



FIGS. 35 and 36. Scheme for sex-determination and sex-linkage in the Indian 

 runner duck. 



A indicates autosomes. 



Z (double lined) indicates sex-chromosome carrying a dominant sex-linked gene, 

 also carrying a preponderance of male-tendency genes. 



Z (single lined) indicates sex-chromosome carrying a recessive sex-linked gene, 

 etc. 



W indicates the large sex-chromosome carrying female-tendency genes only. 



w indicates the smaller sex-chromosome which carries likewise female-tendency 

 genes only. 



