Chromosomes in Living Organisms. 283 
cation wfere maintained either by the development of a number 
of oospores, as in certain Fucaceae; or, in addition to the 
sexual organs, altogether new organs were developed to ensure 
rapid and vigorous development of new individuals in an 
asexual manner. This took place in various ways. Either 
asexual reproductive organs were intercalated in the life- 
history of the original generation, or an altogether new asexual 
generation was developed from the product of the sexual act. 
The independent individualization of these different stages of 
development of the sexual generation into special organs for 
vegetative multiplication, or into distinct bionts, was carried 
out to the highest degree in the Fungi and led to the evolution 
of the many different reproductive forms occurring, for in- 
stance, among the Ascomycetes. These arrangements for 
asexual reproduction were so efficient in the Fungi that the 
result was the disappearance of the sexual organs and of 
sexual reproduction. In the Mosses, on the one hand, and in 
the Vascular Cryptogams and Phanerogams, on the other, 
there sprang an altogether new generation from the product 
of the sexual act, the function of which is to reproduce 
asexually a large number of individuals. The degree of 
development attained by this generation differed accordingly 
as its activity was entirely limited to reproduction, or included 
also nutritive functions. In the Muscineae, this generation is 
restricted to the asexual multiplication of the individual, and 
hence it is, in these plants, the sexual generation in which the 
thallus has attained cormophytic differentiation into stem and 
leaf. In the Vascular Cryptogams, the centre of gravity of 
phylogenetic evolution is transferred to the asexual generation 
springing from the product of the sexual act : this is the 
generation which, in these plants, attained and advanced in 
cormophytic differentiation. In proportion as this evolution 
took place, the nutritive apparatus of the sexual generation 
became of less importance ; and it became altogether super- 
fluous from the moment when the asexual generation began 
to provide its spores with the material necessary for the 
development of the sexual generation. In accordance with 
