210 Secondary Male Chai^acters in a Pheasant 



If this be true of these Hermaphrodites it is also probably true of normal 

 individuals, all of whom are Hermaphrodites in some degree. In other 

 words in addition to the sex gland with its Hormonic secretion, we 

 must also recognise a somatic or peripheral factor in the causation of 

 secondary sex characters. No amount of Hormone will bring about the 

 development of secondary male characters in individuals, and in tissues, 

 in which the rudiments of such characters are absent. On the other 

 hand sex gland and somatic rudiments being given in heredity, the due 

 development, and the continued growth of the sex character, depend 

 on the presence of the sex gland and on the integrity of its internal 

 secretion. 



Without the help of some such somatic, or tissue factor, it is very 

 difficult to explain these unilateral cases by any Hormonic theory even 

 if we invoke the aid of the nervous system. 



There are some further facts which support this view. Thus, as 

 Shattock has pointed out, all secondary sex characters are not equally 

 dependent for their growth and development on the internal secretions 

 of the corresponding sex glands. See the case of the male Leghorn 

 chick in the Royal College of Surgeons Museum in which the pre- 

 cocious development of the testes was associated with a fully formed 

 male comb, but in which this testicular activity failed to bring about 

 the growth of spurs, or sickle tail feathers, another male character. 

 Comb and spurs and sickle tail feathers stand on a different footing 

 then in this respect, and it is also known that hens occasionally develop 

 spurs while continuing to lay fertile eggs. The somatic tissues which 

 contain the rudiments of the secondary sex characters differ in their 

 susceptibility to the influence of the corresponding sex gland Hormone, 

 and it is quite conceiva^ble that in these hemilateral cases tissues which 

 are genetically homozygous in respect of the male or female character, 

 tissues which have as it were received a double dose of femaleness or 

 maleness, are more susceptible to the influence of their con-esponding 

 Hormone than tissues which are heterozygous (or singly dosed) in 

 respect of such sex qualities. 



Examination of the tail feathers. 



The peculiar arrangement of the pigment pattern in the individual 

 tail feathers of this bird is of interest in this connection. From a 

 cursory examination of some skins in the Natural History Museum 

 S. Kensington, I am inclined to think that hemilaterality of male 

 plumage pattern in individual tail feathers goes with hemilaterality of 



