02642cam a22003613u 450000100060000000300070000600500170001300600020003000700050003200800410003701000130007804000110009104100170010205000070011910000360012624500830016226400510024530000470029633600260034333700260036933800360039549000590043150000310049050802340052152013180075553400450207365300120211865300180213065300130214883000590216185600430222099900170226357460UtSlPG20260610134326.0mcr n260607r2018||||utu|||||o|||||||||||||| d  a19014430  aUtSlPG 7aen2iso639-1 4aQH1 aMorgan, Thomas Hunt,d1866-194514aThe genetic and the operative evidence relating to secondary sexual characters 1aSalt Lake City, UT :bProject Gutenberg,c2018  a1 online resource :bmultiple file formats  atextbtxt2rdacontent  acomputerbc2rdamedia  aonline resourcebcr2rdacarrier1 aCarnegie Institution of Washington publication no. 285  aRelease date is 2018-07-07  aProduced by Larry B. Harrison, Bryan Ness, Chuck Greif and
the Online Distributed Proofreading Team at
http://www.pgdp.net (This file was produced from images
generously made available by The Internet Archive/American
Libraries.)  a"The Genetic and the Operative Evidence Relating to Secondary Sexual Characters" by T.H. Morgan is a scientific publication written in the early 20th century. This work delves into the genetic and physiological aspects of secondary sexual characteristics in birds, particularly focusing on the Sebright bantam and other fowl as subjects for analysis. It covers various experiments and findings related to plumage differences between hen-feathered and cock-feathered males, exploring how these traits are influenced by factors such as heredity and endocrine signaling.  The opening of the book sets the stage for an in-depth study of the genetic mechanisms at play in determining secondary sexual characteristics. It begins with a discussion of the existence of two male types within certain poultry breeds and introduces the author's experimentation with castrating hen-feathered Sebrights to observe changes in plumage. Morgan recounts his observations regarding the physical alterations in feathering post-operation, revealing insights into the relationship between the gonads and plumage expression. This portion establishes not only the methodology and initial findings but also hints at the broader implications for understanding sexual differentiation in birds. (This is an automatically generated summary.)  nOriginal publication data not identified  aPoultry  aSex (Biology)  aGenetics 0aCarnegie Institution of Washington publication no. 28540uhttps://www.gutenberg.org/ebooks/57460  c98291d98291