Persistence of the left systemic aortic arch in the chick
Persistence of the left systemic aortic arch occurs frequently in Light Sussex and less commonly in Rhode Island Red chickens as classified on hatching. Some degree of genetic control of this variant within the Rhode Island Red breed is indicated by differences in the incidence of the anomaly in the offspring of individual cooks and hens. Significant differences between hatches indicate the existence of environmental influences of unknown origin.
I wish to thank Dr H. Grüneberg for his encouragement and advice, Eric Maddison of Wye College for assistance with the statistical work and Professor M. M. Cooper for the supply of material from the College Farm. I am also grateful to my wife for drawing the text-figures.
Volume 100, 2021
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