Evolution in the Plant Kingdom. 331 
form also. To the one phase is assigned sex-reproduction ; to the 
other the dissemination of the plant by asexual spores. The ordi- 
nary vegetative structures, representing root, stem, and leaves in 
the higher groups, are here included in the sex-phase also; so this 
phase is the prominent‘one, the one ordinarily observed and spoken 
of as “the plant ;” while the asexual phase is more inconspicuous, 
and, being mechanically borne on the other, seems to be but a 
part of it. 
From this point on, the tendency is to confine the sex-phase 
more and more entirely to the business of sex-reproduction, and to 
transfer the vegetative structures more and more completely to the — 
asexual phase. The result is, that as we advance towards the 
higher groups the sex-phase becomes less and less prominent, as the 
function is taken away from it which involves size and display ; 
while the asexual phase, taking on the function involving display, 
becomes more and more prominent, and is popularly styled “the 
plant.” So that, while “the plant” in the case of mosses is the 
sexual phase in the life-cycle, “the plant” in higher groups is very 
probably the asexual phase, representing the so-called “ fruit” of 
the moss, As the sex-phase is to be more and more confined to 
Sex-reproduction, it can easily be understood how it can be reduced 
more and more, until it has only the cells actually needed ; and these 
cells may be reduced to two, one to represent the plant, and the 
other the sex-organ growing upon it. This seems to represent the 
goal set before the sex-phase, when in the sixth group the vegeta- 
tive structures begin to leave it. From this point on evolution 
reduces and simplifies the sex-phase, increases and makes more and 
more complex the asexual phase. The sex-phase thus begins 
simply in the lowest groups and ends simply in the highest, reach- 
mg in the fifth probably its greatest complexity. While this is 
true of the structure of the sex-phase, it is not true of the sex- 
function, for the very highest possible degree of differentiation in 
this regard is attained in the highest group. 
In the sixth group, represented by ferns and their allies, we 
find a very wide distinction between the sexual and asexual phases ;. 
the latter having become very prominent and having possessed 
itself of most of the vegetative structures, being the ordinary fern- 
Plant, with its great display of vegetative structures and asexual 
Spores, but no sex-organs. Linneus may well have examined 
