196 THE HISTORY OF CREATION. 
different generative substances, the male sperm and the 
female egg, are either produced by one and the same indi- 
vidual hermaphrodite (Hermaphroditismus), or by two 
different individuals (sexual separation, Gonochorismus) 
(Gen. Morph. ii. 58, 59). 
The simpler and more ancient form of sexual propagation 
is through double-sexed individuals (Hermaphroditismus). 
It occurs in the great majority of plants, but only in a 
minority of animals, for example, in the garden snails, 
leeches, earth-worms, and many other worms. Every single 
individual among hermaphrodites produces within itself 
materials of both sexes—eggs and sperm. In most of the 
higher plants every blossom contains both the male organ 
(stamens and anther) and the female organs (style and 
germ). Every garden snail produces in one part of its 
sexual gland eggs, and in another part sperm. Many her- 
maphrodites can fructify themselves ; in others, however, 
copulation and reciprocal fructification of both hermaphro- 
dites is necessary for causing the development of the eggs. 
This latter case is evidently a transition to sexual separa- 
tion. 
Sexual separation (Gonochorismus,) which characterizes 
the more complicated of the two kinds of sexual reproduc- 
tion, has evidently been developed from the condition of 
hermaphroditism at a late period of the organic history of 
the world. It is at present the universal method of propa- 
gation of the higher animals, and occurs, on the other hand, 
only in the minority of plants (for example, in many aquatic 
plants, eg. Hydrocharis, Vallisneria; and in trees, eg. 
Willows, Poplars). Every organic individual, as a non- 
hermaphrodite (Gonochoristus), produces within itself only 
