GENE H AND TESTOSTERONE 

 IN THE FOWL 



IN MANY birds the plumage of the male is appreciably different from that of 

 the female. Such a difference is particularly noticeable in the Phasianidae , 

 of which the common fowl is a familiar example. But there are also species 

 in which this dimorphism in plumage does not occur, and even in the domestic 

 fowl some races fail to show it. In these races, while other secondary sexual 

 characters are essentially as usual, the plumage of the male is almost identical 

 with that of the female. This type of feathering is called henny* and has been 

 shown to be clue to a dominant autosomal gene designated as H. Males that 

 are homozygous {HH) and usually those that are heterozygous (H/i) for this 

 gene are characterized by henny plumage, while those homozygous for the 

 recessive allele {hh) develop the normal cocky plumage. Females of the 

 formulas HH and hh are indistinguishable except by genetic or involved 

 endocrine tests. This interesting situation raises the question of how gene H 

 is related to other genes and how it affects feather development. In this paper 

 the role of gene H in relation to testosterone will be considered. 



The heredity of hen-feathering in the male was studied many years ago by 

 T. H. Morgan, by R. C. Punnett, and by a number of others, all of whom were 

 fairly unanimous in their interpretation of the genetic behavior of the trait. 

 More recently Punnett^ has suggested that the normal locus of the H allele is 

 in the Y chromosome of the female and that it becomes autosomal and po- 

 tentially present in the male only through translocation. This hypothesis may 

 explain several puzzling observations that are on record, but whatever the 

 exact cytological relations may be, the somatic manifestation of the gene has 

 been known for a long time and in many different breeds. There are several 

 records of new appearancesf which may reasonably be attributed to fresh 

 mutations or, on Punnett's theory, to translocations following earlier muta- 

 tions. In any event, when the gene once appears in an autosome its subsequent 

 genetic behavior is fairly simple. There is no evidence known to the writer 

 which suggests that the trait may have a prototype in any wild species. 



* In early days when cock fighting was permissive in England there were some pit games 

 in which the males Avere hen-feathered and, because of the supposed advantages accruing 

 from such a camouflage, hen-feathered cocks attained a certain popularity. In the argot of 

 the day they ^\•ere called "hennies" — whence, presumably, our current scientific term henny 

 and, by analogv, its correlative cocky, terms which are now used to characterize the two dis- 

 tinctive types of phuiiage that may occur in male fowls. 



f As long ago as 1873, Tegetmeier," whose name appears often in Darwin's Animals and 

 Plants under Domestication, recorded one fresh occurrence of the trait. A game bantam "of 

 known purity" which hatched in the spring of 1859 at first developed normal plumage, after 

 which it became 'strictly hen-feathered both as to form and colour" and produced some hen- 

 feathered male offspring. Others of its offspring were normal and took second prize at the 

 Crystal Palace show. It was exhibited at a meeting of the Zoological Society on March 16, 1861 . 

 "Nothino would have been easier than to have established a permanent breed," said Teget- 

 meier — and he was probably right. 



[ '59;] 



