THE ASCENT OF THE BODY 



contain any bone at all, but only a shadow or 

 prophecy of it in cartilage. The cartilaginous 

 notochord of the Amphioxus nevertheless is the 

 progenitor of all vertebral columns, and in the 

 first instance this structure appears in the human 

 embryo exactly as it now exists in the Lancelet. 

 But this is only a single example. In living 

 Nature there are a hundred other animal character- 

 istics which at one stage or another the biologist 

 may discern in the ever-changing kaleidoscope of 

 the human embryo. 



Even with this addition, nevertheless, the human 

 infant is but a first rough draft, an almost form- 

 less lump of clay. As yet there is no distinct 

 head, no brain, no jaws, no limbs ; the heart is 

 imperfect, the higher visceral organs are feebly 

 developed, everything is elementary. But gradually 

 new organs loom in sight, old ones increase in 

 complexity. By a magic which has never yet been 

 fathomed the hidden Potter shapes and re-shapes 

 the clay. The whole grows in size and symmetry. 

 Resemblances, this time, to the embryos of the 

 lower vertebrate series, flash out as each new step 

 is attained — first the semblance of the Fish, then 

 of the Amphibian, then of the Reptile, last of the 

 Mammal. Of these great groups the leading em- 

 bryonic characters appear as in a moving pano- 



