MYSTERIES OF LIFE AND MIND 



even in the lower forms, by the same simple reac- 

 tions of light and heat, chemicals or gravity, was 

 undreamed of. 



Taking one of the lower animal forms, plantlike 

 affairs called the hydroids, Dr. Loeb cut from its 

 body a cube. Quite without regard to which side 

 was uppermost, from the top grew the tentacles or 

 branches which form the head, from underneath 

 the roots. If, when growth was partly complete, 

 the piece was inverted, or even if a naturally grown 

 hydroid be turned upside down, from beside the up- 

 turned roots came a head, from beside the deposed 

 head a growth of roots. 



If, in the body of a little affair named, from its 

 gracefully branching head, the cerianthus, an in- 

 cision was made, any place, promptly came a new 

 mouth, with its ring of tentacles. Sometimes, if 

 the cut was small, only the tentacles grew. But 

 these would grip food (rejecting wads of paper and 

 things) and draw it in just as if a mouth was there. 

 If the two mouths, the new and the old, were close 

 enough together so as both to touch the same piece 

 of food, a fight ensued. If the same sort of a con- 

 test be provoked between the tentacles of the nat- 

 ural mouth and those from an incision where no 

 new mouth had been formed, sometimes the blind 

 " mouth" gets the food, and the animal can thus be 

 led to involuntary suicide. 



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