226 



TIIK GENESIS OF SPECIE;-;. 



[Chap. 



In sucn creatures we sec that, from time to time, one of 

 the segments of tlie body gradually becomes modified till it 

 assumes the condition of a head and this remarkable phe- 



AN AKVEI.rD DrrrDING SP0NTANE0TT8LT. 



(A new head havuig been formed toward the hinder end of the body of the parent.) 



nomenon is repeated again and again, the ])ody of the worm 

 thus multiplying serially into new individuals which succes- 

 sively detach themselves from the older portion. The 

 development of such a mode of reproduction by " Natin-al 

 Selection " seems not less inexplicable than docs its contin- 

 ued performance through the aid 'of "pangenesis." For 

 how can gemmules attach themselves to others to which 

 they do not normally or generally succeed ? Scarcely less 



