<3HAP. XIX.] WHAT EVOLUTION MEANS : ORGANIC EVOLUTION. 153 



Animals are the descendants, through a long series of modifications or 

 transformations, or both, of a limited number of an ancient simpler 

 type. We must not suppose that this change has gone on as if things 

 were simply mounting a ladder ; the truth seems to be that we have 

 to deal with a sort of tree with a common root and two main trunks 

 representing animal and vegetable life ; each of these is divided into a 

 few main branches, these into a multitude of branchlets, and these 

 into smaller groups of twigs. 



This new view represents to us the evolution of the sum of living 

 beings; shows that all kinds of animals and plants have come into 

 existence by the growth and modification of primordial germs. Now I 

 want just to say that this is no new idea, it is the demonstration which 

 is new to us in our present century and generation ; we have really to 

 go back to the seventeenth century, if indeed we must not go as far back 

 as Aristotle, for the first germs of it ; but with regard to the history, 

 however, I have no time to deal with it. There are two or three 

 points, however, to be considered in regard to this evolution. The 

 individual organic forms need not continuously advance, all that is 

 required is that there shall be a general advance an advance like that 

 of our modern civilisation while some individual tribes or nations, as 

 we know stand still, or become even degenerate. With this reserva- 

 tion, the first forms were the simplest. It may be that as yet we know 

 really very little of the dawn of geological history; that the fossili- 

 ferous rocks are nowhere near the real base. This conclusion has been 

 derived by Professor Poulton* from the complexity of the forms met 

 with in them ; still we find that we have not to deal with such a vast 

 promiscuous association of plants and animals of lowest and highest 

 organisation as we know to-day; we deal relatively only with the 

 simplest. The story both with regard to plants and animals is alike 

 in this respect. 



Let me deal with the plants first. The first were aquatic that is 

 to say, they lived in and on the waters. So far as we know, the first 

 plant life was akin to that of the algae, which include our modern sea- 

 weed, moss-like plants followed them, and then ferns, and it is only 

 very much later that the forms we know as seed plants with gaily 

 coloured flowers living on the land made their appearance. The 

 general trend of change amongst the plants has been in the direction of 

 a land vegetation as opposed to one merely in or on the surface of the 

 waters, and some present seaweeds exhibit the initial simplicity of 

 plant-structure which characterised the beginning of vegetable life, 

 while the seed plants I have mentioned are of comparatively late de- 



* Presidential Address, Section D, British Association Meeting at Liverpool, 

 1896. 



