CHROMOSOMES OF INDIAN RUNNER DUCK. 353 



Wilson, E. B. 



'25 The Cell in Development and Heredity, Ed. 3. New York, The Macmil- 

 lan Co. 



EXPLANATION OF PLATES. 



All figures from the Duck are reproduced at the same scale. The drawings 

 were outlined with an Abbe camera lucida at a magnification of 3,500 diameters, 

 obtained with a Spencer 1/12 homogeneous immersion objective and a Zeiss i8x 

 compensating ocular with draw tube set at 150 mm. and drawing made at the level 

 of the base of the microscope. The drawings were then enlarged by means of a 

 copying camera lucida to 7,350 diameters. Having been reduced one half in the 

 reproduction, they now appear at a magnification of 3,675 diameters. 



W, the large sex-chromosome carrying female-tendency genes only, 

 w, the smaller sex-chromosome which carries likewise female-tendency genes only. 

 Z, sex-chromosome carrying a preponderance of male-tendency genes and also sex- 

 linked genes. 



cr, cresent-shaped autosomes No. 32. 

 38Z, same as Z. 

 38w, same as w. 

 37 to i, autosomes. 



