A LIMB FOR A LIFE 167 



sisting in a prolonged endeavor along a line which 

 is certainly not that of least resistance, which leads 

 to a reward not immediately, but only eventually. 



Perhaps Nature would not have put her natural 

 selection stamp of approval on the asteroid's 

 autotomy if individual starfishes had not approved 

 of it themselves. We are not prepared indeed to 

 say what form the brainless creature's approval 

 might take, but we get an indication of it perhaps 

 in approvals given by our subconscious self. Quite 

 in the opposite direction is another saving-clause, 

 that cases of a rat or a stoat cutting itself free from 

 a trap by amputating a limb, belong to a category 

 different from and higher than that of starfishes or 

 crabs which illustrate typical autotomy. 



The highest level at which autotomy is practised 

 is among lizards, many of which need but little 

 provocation to induce them to surrender their tail 

 to their assailant an expedient that often saves 

 their life. The specific name of our British limbless 

 lizard (Anguis fragilis) registers the uncanny readi- 

 ness with which it surrenders the tail of its snake- 

 like body. That lizards have taken ages to bring 

 their life-saving curtailment to perfection seems 

 probable, especially when we notice that in many 

 forms there is a special breakage area, and that 

 a weak line has been established affecting skin, 

 muscles, connective tissue, and backbone. Up the 

 middle of the vertebra there is a soft zone, the 

 breakage plane, across which the tail snaps in the 

 autotomy. What is lost by the amputation can 



