DEGENERA TION. 



43 



Now let us look at the internal organs (Fig. 17). 

 There are four structures, which are all foiw pos- 

 sessed at some time of their lives by all those 

 animals which we call the Vertebrata, the 2:rcat 

 branch of the pedigree to which fishes, reptiles, 

 birds, beasts, and men belong. And the combina- 

 tion of these marks or structural peculiarities is an 

 overwhelming piece of evidence in favour of the 



SPINAL CHOKO 



NOTOCHORD 



POSITtON OE SPIRACLE CILLSLITSli 

 SPINAL CHORD / .braIN MoItH 



NOTOCHORD 



CILU SLITS 



Fig. 17. — Tadpole of Frog and of Ascidian. Diagrams representing the chief 



internal organs. 



supposition that the creatures which possess this 

 combination are derived from one common ancestor. 

 Just as one would conclude that a man whom one 

 might meet, say on Salisbury Plain, must belong 

 to the New Zealand race, if it were found not 

 only that he had the colour, and the hair, and the 

 shape of head of a New Zealander, but also that he 



