PROGRESS, A NECESSARY RESULT. 279 
the group of Ferns or Filicinz (ferns, pole-reeds, scale- 
plants, etc.). But as yet there existed no flowering plants, 
or Phanerogama. ‘These originated later with the Gymno- 
sperms (firs and cycads), whose whole structure stands far 
below that of the other flowering plants (Angiosperms), and 
forms the transition from the group of fern-like plants to the 
Angiosperms. These latter developed at a still later date, 
and among them there were at first only flowering plants 
without corolla (Monocotyledons and Monochlamyds) ; only 
later were there flowering plants with a corolla (Dichlamyds). 
Finally, again, among these the lower polypetalous plants 
preceded the higher gamopetalous plants. The whole series 
thus constitutes an irrefutable proof of the great law of pro- 
gressive development. 
Now, if we ask what is the cause of this fact, we again, 
just as in the case of differentiation, come back to natural 
selection in the struggle for life. If once more we consider 
the whole process of natural selection, how it operates 
through the complicated interaction of the different laws 
of Inheritance and Adaptation, we shall recognize not 
only divergence of character, but also the perfecting of 
structure to be the direct and necessary result of it. We 
can trace the same thing in the history of the human race. 
Here, too, it is natural and necessary that the progressive 
division of labour constantly furthers mankind, and urges 
every individual branch of human activity into new dis- 
coveries and improvements. This progress itself universally 
depends on differentiation, and is consequently, like it, a 
direct result of natural selection in the struggle for life. 
