THE EVOLUTION THEORY 1'27 



caecum, with the vermiform appendix. In herbivorous mammals 

 a structure of considerable size, and of great importance in the 

 assimilative act, it is much smaller, and often absent, in carnivorous 

 animals. In man the caecum is small and insignificant, playing 

 probably a small part in the absorption of the digested food. But 

 its appendix, the notorious Processus vermiformis, has no function 

 or value whatever, its object being rather, apparently, to create 

 suffering. Its extremely variable length, ranging, in an adult, 

 from 25 cm. to a mere vestige, seems to support this con- 

 ception, which is further proved by the fact that it may be 

 completely removed by a surgical operation without any 

 subsequent injury to the body. 



Many travellers in Africa and Australia have reported the 

 existence of human beings with long hairy tails, but further 

 investigations have always proved these reports to be due to errors 

 or deception. Many savage tribes, the Njam-Njam, the Bongas, 

 &c., are accustomed to w r ear as girdles the skins and tails of wild 

 animals, and this habit may have given rise to such fables which 

 should have been discredited at the first report if it had been 

 remembered that even the highest apes have only rudimentary 

 tails. Nevertheless, these reports are not entirely without 

 foundation. We heard before that each human embryo possesses 

 a rudimentary tail, consisting of a few vertebrae. In most cases 

 this vestigial tail soon becomes degenerate, nor is it even dis- 

 cernible in adult man. Yet now and then we hear of the forma, 

 tion of a typical tail-stump, as shown in the picture of a small 

 Indian child (fig. 36). There are even cases known in which 

 the tail attained a length of about 10 centimetres. 



Among the invertebrates we find numerous facts supporting 

 the Doctrine of Descent. Everyone knows the extremely varying 

 structure of the different classes of the Echinodermata, the sea- 

 urchins and starfishes, the elegant ophiuroids, and the ungainly 

 holothurians. Who would think that all these forms are closely 

 related? Yet in spite of the numerous external differences 

 their organization is surprisingly uniform. This is best shown 

 by their remarkable organs of locomotion which distinguish them 

 from all other animals. 



Those who have seen Echinoderms in an aquarium must 

 have been impressed by their beautiful radially-symmetrical 



