PEOGEESS, A NECESSARY RESULT. 279 



the group of Ferns or FilicinsD (ferns, pole-reeds, scale- 

 plauts, etc.). But as yet there existed no flowering plants, 

 or Phanerogama. These originated later with the Gynmo- 

 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. 



