NATURAL HISTORY STUDIES 



taken ages to bring their life-saving curtailment 

 to perfection seems probable, especially when we 

 notice that in many cases there is a special breakage 

 plane, a weak line going through the whole tail, 



including the backbone. 

 What is lost can be 

 regrown at leisure, though 

 not with the original 

 finish. Newts and sala- 

 manders (and the tadpoles 

 of frogs and toads) have 

 great powers of regrowing 

 parts that have been bit- 

 ten off, but, so far as we 

 know, lizards are the 

 only backboned animals 

 that show surrender of 

 parts. Among backbone- 

 less animals, however, it 

 occurs often. We find it, 

 for instance, among sea- 

 Common Starfish (A^erias ru- slu g s and ther MoUuscS, 

 bens) regenerating lost parts, and in many different kind 



It shows at the top two arms T> 4-u TD i i 



which are just beginning to of Worms. In the Palolo 



be regrown. Below we see worm, which burrows in 



that the largest of the five 4.1^ ^ i ,,^-f ! -u 



arms has been previously the coral-reefs, nearly the 



regrown double. (After whole of the body is 



broken off at the breeding 



season and bursts in the water, liberating tens of 

 thousands of germ cells, while the head remains 

 in the rock and makes a new body by and by. 

 Among starfishes, brittle-stars, feather-stars, and sea- 



232 



