KINDS OF MULTIPLICATION 43 



that we do not stop to realize its meaning. It means that 

 lost parts can be regrown. Now we humans could not 

 grow a new arm or even a new finger. We do not have 

 much power of regenerating lost structures, but we have 

 enough to heal wounds. 



If a lizard loses its tail, it is said that it does in some 

 degree grow again. In crayfishes, if antennae or other 

 appendages be lost, new ones may grovvr out. This 

 suggests that this power is seen to better advantage in 

 the lower than in the higher animals. It is even more 

 true in animals still lower. In the earthworm it has been 

 shown that the head, brain, mouth and all necessary 

 anterior organs may be cut away. If this is done some 

 six or eight segments back of the head, all these lost 

 organs will be formed again in front of the cut. Similarly, 

 new posterior organs will be regenerated if posterior 

 segments are removed. 



In hydra, which is one of the very simplest of the many- 

 celled animals, it is said that any length of the body 

 .anywhere may be able to regenerate all the lost parts. 



