GROWTH OF THE METAMERA. 349 



in the Worms, we find that it results, in consequence of 

 repeated asexual generative processes, in consequence of 

 what is called terminal budding, from an originally inarticu- 

 late Worm-body, which is equivalent to a single metameron. 

 Thus the Tape-worm embryo is at first all head; and on 

 ihiis head, which is only equivalent to a single metameron, 

 repeated budding gives rise to one metameron after another; 

 all, however, remain connected. So, too, in the Ringed 

 Worms (Annelida) the originally inarticulate body puts out 

 numerous buds from its posterior extremity, thus giving 

 rise to the long articulated chain. Such is the nature of 

 this process, which, however, in the germ-history of Articu- 

 lated Animals and Vertebrates appears much compressed 

 and secondarily modified. Originally, however, every ver- 

 tebrate animal is just such a metameric chain, which has 

 arisen, in consequence of terminal budding, from an in- 

 articulated germ.^^ 



As the metamera arise in this way, it will readily be 

 understood that the anterior primitive vertebrae are earliest 

 found. Such is indeed the case. The earliest primitive 

 vertebrae, which are situated about the centre of the germ, 

 are' the first and second neck-vertebrse. Then come the 

 third and fourth neck-vertebrae, and so on. Each primitive 

 vertebral segment in its turn soon produces, by the process 

 of budding, a new metameron at its posterior extremity, 

 till the chain is complete. The entire jointed body grows, 

 therefore, in a direction from front to rear. In this way 

 the articulated vertebral column of Man is at length pro- 

 duced (Figs. 110, 111). In the developed Man it is composed 

 of the cranium, with a chain of thirty-three or thirty -four 

 different vertebrae : viz., seven neck-vertebrse, twelve chest- 



