276 STUDIES IN THE EVOLUTION OF ANIMALS 



ordinary form, and thus their abnormal character would almost 

 inevitably be lost.' 



In the case of polydactyl monstrosities Darwin himself has 

 shown that this is certainly not the case, the abnormality often 

 seeming to gain strength by dilution with the normal form, and 

 Professor Huxley indorsed this view. 



It seems we are here dealing with ^vords instead of with facts ; 

 for two metacarpal or metatarsal bones, by fusing into one bone, 

 become a monstrosity, although of a lesser degree, as much as if 

 two eyes fused into one. 



We see so many teratological phenomena in man and among 

 domestic animals, originated somehow suddenly that there can be 

 no reason to doubt that in a state of nature similar monstrosities 

 must also have frequently occurred. The majority, no doubt, 

 became extinct from unfitness in the battle of life, but now and 

 again a monstrous individual may have been fitted, not perhaps to 

 carry on the same life as those which bred it, but that very 

 monstrosity may have enabled it to acquire a different habit of 

 life, which may have left it ivithout competitors, and so enabled 

 to live. Then if it bred with the others out of which it evolved, 

 it would sometimes transmit the monstrosity to which it may have 

 owed its life, and so by degrees a new type of animals would 

 come into existence. Having more or less the same habits, they 

 would congregate together and interbreed, and thus fix that 

 monstrosity, so called. 



Among monstrosities might be mentioned the upper canines of 

 the Babirusa, or Pig-Deer, which grow through the upper jaw 

 upwards, and curve backwards over the eyes ; and what is more, in 

 some varieties they seem to be quite useless, as their points almost 

 touch the skin ; so that instead of digging up roots, as other wild 

 pigs do, the Babirusa contents itself with eating fallen fruit. 



