THE EVOLUTION OF MAN 



first fauna and flora fell ready made from heaven. 

 But the fact remains that from this time on we no 

 longer find any remains of the ancient animals 

 and plants, x If we wish to make further concluX 



vsions we can only rely on the now surviving lower 

 and lowest creatures and look for points of con- 

 tact with them in the embryonic stages of higher^ 



^animal sx 



With this understanding, we now proceed to 

 discuss the further evidences on which we may 

 rely from now on. 



Among all the animals now known and living 

 below Amphioxus, there is only one single small 

 group which still shows a direct indication of a 

 backbone, the so-called ascidians. These are small 

 marine animals which -are surrounded by a cloak 

 of wood-like substance, very much as snails sur- 

 round themselves with a well-nigh closed house. 

 To judge by their general construction, these 

 ascidians would be most logically classed among 

 the worms, save for a few points of contact with 

 mollusks. Among these ascidians a fine thread 

 of cartilage appears, which has about the same 

 position as the "chorda" of Amphioxus. Most 

 of them have this cartilage only in the embryonic 

 or larval stage, but a few of them preserve it for 

 life. There is a strong possibility that the ascid- 



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