. Bulletin of the British Ornithologists' Club. 1961 121 Vol. 81 $ 18th Oct. 1954 Habbaniya, Iraq. Collected by Jeffery G. Harrison, in coll. James M. Harrison. It is known that with transient endocrine imbalance the secondary sexual characters in some species, notably in Gallus domesticus, Phasianus colchicus and some of the Anatidae, a swing in these characters towards or away from one or the other sex may result. But as already stated this basis cannot be accepted as responsible for such cases in P. domesticus and Mayr {loc. cit.) comments in this connection, "Rather, it seems p
. Bulletin of the British Ornithologists' Club. 1961 121 Vol. 81 $ 18th Oct. 1954 Habbaniya, Iraq. Collected by Jeffery G. Harrison, in coll. James M. Harrison. It is known that with transient endocrine imbalance the secondary sexual characters in some species, notably in Gallus domesticus, Phasianus colchicus and some of the Anatidae, a swing in these characters towards or away from one or the other sex may result. But as already stated this basis cannot be accepted as responsible for such cases in P. domesticus and Mayr {loc. cit.) comments in this connection, "Rather, it seems probable that most of the sexual dimorphism is genetically fixed in the feather papillae". We know that an appearance of pseudo-feminisation can result from an imbalance of the thyroid secretion. This has been produced experimentally by Zawadowsky (^^) and his colleagues and has been recorded in the wild. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original British Ornithologists' Club. London : British Ornithologists' Club
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