high 
But in 
1884. ] The Theory of Sex and Sexual Genesis. 677 
time cause the development of the organs that are redundant to 
that sex to be so completely arrested that not even rudiments of 
them should appear. This explanation agrees with and also ex- 
plains a law of variation enunciated by Darwin, namely, that 
“variations which appear early in life in either sex, tend to be de- 
veloped in both sexes” (“ Descent of Man,” p. 232). 
The existence of rudimentary sexual organs is thus, I think, 
satisfactorily accounted for, without assuming that they represent 
organs that were once functional in the sex in which they are 
found. In the course of descent of a species it is the common 
type of the species—which is redundant as regards the organs 
that are required to be functional in either one of the sexes— 
that undergoes modification by adaptive variation, and by the 
natural selection of irrelative variations through the succession 
of the best reproducers. Those organs of the redundant type 
that are functionally proper to either one of the sexes have their 
characters determined by natural selection acting within that sex. 
But if, owing to the conditions above explained, a developed 
Organ in one sex is represented by a rudiment in the opposite 
x, any modification of this part of the common type will not 
only appear in the developed organ of the one sex, but also and 
correspondingly in its rudiment in the opposite sex. Thus, for 
the higher animals at least, the rudimentary sexual organs are 
to be regarded as having been acquired as rudiments in the sex in 
ch they are found, and not as representing organs that were 
once functional in that sex. This explanation accords with the 
fact that such rudiments are most perfectly formed in the highest 
animals 
N 
tive į 
actual 
type aE urse of modification by which the present reproductive 
“YPE o 
of 
the species has been reached, has been by the reduction 
organs that were once functional to a rudimentary state, or by 
5 Eamon of the rudiments as parts of the common repro- 
© type of the species. 
(To be continued.) 
