94 The Mechanistic Conception of Life 



whole new oral pole grows out, but otherwise it too shows 

 polarization. 



A good many animals, so far as we know, reproduce only 

 the lost organ, but never show any heteromorphism. We see, 



Fig. 31. — From nature. Formation of a second head in Cerianthus alter a 

 lateral incision at b. Only a fraction of the norma] number of tentacles are formed 

 corresponding to the fraction of the periphery laid bare by thj incision. No new 

 mouth is formed, but if a piece of meat is offered to the group of tentacles at b 

 they seize it and press it to the place where a mouth ought to be, showing the 

 purely machine-like character of all tliese reactions. 



therefore, that while in some animals we are able to produce 

 heteromorphosis, in others the most definite polarization exists, 

 and we are able to produce regeneration of lost parts only in the 

 arrangement which exists in the normal animal. In this case 

 we must assume that unknown internal conditions determine 

 the arrangement of limbs. 



In addition to examples of heteromorphosis or polarization 

 occurring separately, we find cases in which both phenomena 



