82 



EVOLUTION, GENETICS, AND EUGENICS 



poid apes continue to present the rudimentary vestiges of a tail in a 

 few caudal vertebrae below the integuments, we might well expect to 

 find a similar state of matters in the case of man. And this is just 



Fig. 15. — Diagrammatic outline of the human embryo when about seven 

 weeks old, showing the relations of the limbs and tail to the trunk. (After Allen 

 Thompson.) r, the radial, and u, the ulnar, border of the hand and forearm; 

 /, the tibial, and/ the fibular, border of the foot and lower leg; au, ear; u , spinal 

 cord; u , umbilical cord; b, bronchial gill slits; c, tail. (From Romanes.) 



^vfPyfl-sh/ods ha. 



dvky<?oRES cocc/diS Mtf ■ 



FoiT.S/iCkp-toCdji 

 CoccYX.. 



Fig. 16. — Front and back view of adult human sacrum, showing abnormal 

 persistence of vestigial tail muscles. (From Romanes.) 



what we do find, as a glance at these two comparative illustrations 

 will show (Fig. 14). Moreover, during embryonic life, both of the 

 anthropoid apes and of man, the tail much more closely resembles 



