THE GENETICS OF HABROBRACON JUGLANDIS ASHMEAD 



ly at points of muscle attachment and the last 

 parts to become light in higher temperatures 

 are the regions where muscles attach vertical- 

 ly, (3) animals bred at lov/er temperatures are 

 larger and darker than those at higher, but at 

 a given temperature the smaller animals are the 

 darker, and (4) changes in temperature at any 

 time between egg stage, four days before laying, 

 and prepupal stage, affect adult coloration. In 

 a later study (1934) he shows that increase or 

 decrease of oxygen content of the atmosphere 

 increases pigmentation; and he concludes that 

 variation of oxygen concentration influences 

 the oxidations concerned with pigment formation, 

 indirectly as a non-specific stimulus on the 

 organism as a whole. Kuhn (1927) has shown by 

 selection and by crossing that heredity plays a 

 considerable part in color determination. He 

 argues for a hereditary cytoplasmic influence. 

 P. W. Whiting (1926a) has demonstrated linkage 

 of a gene affecting color of raesosternum with a 

 gene determining defects in wing vein, R4. An 

 extensive series of experiments indicates con- 

 siderable genetic independence of various body 

 regions as well as both linkage and physiologi- 

 cal correlation with certain mutant genes. 



Despite the great range of variability in 

 diverse regions of the body, bilateral symmetry 

 is the rule with very rare exceptions. An oc- 

 casional defective specimen with asymmetrical 

 morphological malformation is likely to show 

 correlated changes in pigmentation. There have 

 likewise occurred a few specimens with an ir- 

 regular mottling of color, but this appears to 

 be pathological. Instances in which specimens 

 of normal form and non-mosaic for mutant traits 



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