1884. ] The Thevry of Sex and Sexual Genesis. 781 
the individual in some of its sexual characters, and especially in 
what Hunter and Darwin have called the secondary sexual char- 
acters, is determined in great part by vital correlations between 
the parts thus developing and the sexual glands, established 
through the nervous system. This is clearly shown by the effect 
that is produced on the development of these parts by the remo- 
Val of the sexual glands. 
In moncecious and dicecious plants it is the reproductive mem- 
ber of the composite individual that undergoes a one-sided devel- 
opment. And the course of development is determined by a 
similar bias in the formative conditions—if not extending through- 
out the whole plant, at least in some manner initiated and main- 
_ tained at the point from which the flower is developed. The 
a peduncle and receptacle, one or both of which parts are common 
_ toall classes of flowers, and which are necessary to the develop- 
= ment of the sexual organs proper, have their developmental 
_ ‘Capacities in every case adapted to their required functions; and 
their functions in plants in which the sexes are separate consist in 
giving support and transmitting nourishment to a set either of 
male or of female flowers, but not to sets of both. A receptacle, 
‘specially, which is required to bear organs of one sex only, 
will admit of being smaller and of more uniform structure than 
one which is required to perform the double function of bearing 
~> Stamens and pistils ; and a difference of a similar kind must 
“st between the peduncles in the two cases, As the. required 
Structure of these parts in unisexual flowers is somewhat differ- 
Mir the two sexes, there is thus established not only a reduc- 
tion in developmental capacity of these parts, but also a sort of 
: Structural dimorphism. And as these parts are not in themselves 
mas, they tend, even when developing under conditions of an 
: “actly medium character between those most favorable to the 
‘Production of the male generative element and organs, on the one 
“hand, and those most favorable to the production of the female 
Parts, on the other hand, to assume the form suitable to one or 
the other alone. 
In the higher animals that bias of the formative conditions 
“termines the sex is probably initiated, in most cases a 
Mader normal conditions, in the ovum at the time of its fertiliza- 
? Or it may even depend on the constitution which one or the 
T the combining cells has, previous to their union. But it 
