MIRACLES OF SCIENCE 



organs, and it will be obvious that this series of ex- 

 periments resulted in an amazing multiplication of 

 personalities. 



Experiments of this, type may be so modified as 

 to result in growing multiple heads on a single body. 

 Professor T. H. Morgan has been able to produce a 

 two-headed earth worm, by cutting off the anterior 

 end and then excising a piece of the central nerve 

 cord, so that two anterior nerve ends remained, from 

 each of which a head developed. Dr. Van Duyne, 

 at Professor Loeb's suggestion, extended the experi- 

 ment to planarians with such success as to grow not 

 merely two but as many as six heads to an individual, 

 each head with its normal pair of eyes. 



Possibly the ancient Greeks were led to conceive 

 the idea of the hydra-headed monster from observa- 

 tion of a planarian that through some accident had 

 been similarly led to develop multiple heads. 



As showing that the diverse heads thus developed 

 on one body have in truth something of divided per- 

 sonality, we may note Professor Loeb's comment 

 that his double-headed planarian is observed to 

 develop conflicting tendencies. Thus the two heads 

 will struggle for the same piece of meat, regardless 

 of the fact that the same body will receive it which- 

 ever mouth wins. 



Again the two heads may pull in opposite 'direc- 

 tions so strongly as actually to tear the body 

 asunder! 



This growing of hydra-headed monsters is curious 

 enough, but Professor Loeb has juggled with certain 

 other low organisms in a way in some respects even 



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