52 THE PHYSICAL KINSHIP 



Another vestigial organ in the body of man, and 

 one of significance from the standpoint of mor- 

 phology, is the tail. The tail is an exceedingly 

 unpopular part of the human anatomy, most men 

 and women being unwilling to admit that they 

 have such an appendage. But many a person 

 who has hitherto dozed in ignorance on this matter 

 has learned with considerable dismay, when he 

 has for the first time looked upon the undraped 

 lineaments of the human skeleton, that man 

 actually has a tail. It consists of three or four 

 (sometimes five) small vertebrae, more or less 

 fused, at the posterior end of the spinal column. 

 That this is really a rudimentary tail is proved 

 beyond a doubt by the fact that in the embryo it 

 is highly developed, being longer than the limbs, 

 and is provided with a regular muscular apparatus 

 for wagging it. These caudal muscles are gener- 

 ally represented "in gi own-up people by bands of 

 fibrous tissue, but cases are known where the actual 

 muscles have persisted through life (9). 



The nictitating membrane, which in birds and 

 many reptiles consists of a half-transparent curtain 

 acting as a lid to sweep the eye, is in the human eye 

 dwindled to a small membranous remnant, draped 

 at the inner corner. The growth of hair over the 

 human body surface may be regarded, in view of 

 the sartorial habits of man, as a vestigial inherit- 

 ance from hairy ancestors. One of the most 

 notorious of the vestigial organs of man is the 

 vermiform appendix, a small slender sac opening 

 from the large intestine near where the large 



