C. J. Bond 213 



a tendency to divide into two halves of different sex, a male left half 

 and a female right half, and along with this somatic differentiation the 

 sex gland itself also shows a tendency to divide into a female portion 

 and a male portion. Owing further to the fortunate fact that these 

 two sex glands do not functionate coincidently, we have an opportunity 

 of observing a natural experiment, in which the effect of a female 

 Hormone is first exercised simultaneously on the male and the female 

 side of one and the same individual, while at a later stage the male 

 Hormone exerts its influence on the same dual organism, with the 

 result that while in the case of the trunk and limbs the male side only 

 responds to the male Hormone, the tail responds as a whole, but only 

 as regards one side of each individual tail feather. 



Moreover along with, but not as the cause of or consequence of 

 this abnormal somatic segregation, another abnormal segi-egation also 

 occurred in the sex gland by which a dual gland or ovo-testis was 

 formed and in which (as usual) the female portion came into functional 

 activity and retrogressed before the male portion began to develop. 



In some such manner it seems possible to explain the limitation of 

 influence of the male and female sex gland Hormone to opposite sides 

 of the body, for the side which possessed only femaleness and no male- 

 ness (i.e. no somatic rudiments capable of developing male characters) 

 could not respond to the male Hormone, while the side which con 

 tained no female rudiments could not respond to the female Hormone. 

 There is however a difficulty in this explanation, for as I have already 

 pointed out (cf. PI. XI, fig. 6), a well-marked spur rudiment such as 

 normally occurs in the hen pheasant also occurs on the right leg (that 

 is on the female side) in this bird. How are we to interpret this fact ? 

 It is true that it is small and resembles the rudimentary spur in normal 

 female birds. Hence it may be regarded as a " specific " and not as a 

 " sexual " character and so may be considered to be out of the reach of 

 the influence so to speak of the male Hormone. 



Or it may be that this spur rudiment on the right, or female, side 

 represents a single dose of maleness instead of the double dose on the 

 left side, in which as a consequence the spur is well developed. If this 

 be so, then instead of simple " Presence and Absence " of maleness and 

 femaleness the question becomes one of the volume of these factors. 

 The greater volume of the male factor on the left side would then 

 account for the readier response to the stimulus of the male Hormone 

 in the left leg. 



But whether we try to explain the facts by the presence and 



