THE INDIVIDUAL 



39 



much alike. They differ to the same extent that the 

 two sides of any single individual may differ. 



c. The question of the individual may be discussed Processes 



J 'of regenera- 



from another standpoint. When we accidentally knock tion after 

 off a small piece of skin, the wound heals ; but if we mjui 

 lose a finger, no new finger grows in its place. A lizard, 

 however, may lose its tail, and a new tail grows. If the 

 tail is broken at one side, sometimes a tail begins to 

 grow at the point of fracture, and two tails result. 

 Going to a lower level in the scale of animal life, we 

 find that the arm of a starfish, removed with a certain 

 amount of the disk, will grow new arms and eventually 

 form a whole starfish. Many of the lower invertebrates 

 may be divided into two or more parts, and each part 



FIG. 9. Renilla, a compound animal, living in the sea 

 (Phylum Ccelenterata, Order Alcyonaria). 



will regenerate what it lacks, producing a whole in- 

 dividual. This is not the division of ordinary reproduc- 



