IV 

 HETEROMORPHOSIS l 



I. INTRODUCTION 



IT is well known that a number of animals possess the 

 power of forming a new organ in the place of an organ which 

 has been lost. It has always been taken as a matter of course 

 in animal physiology that the regenerated organ is neces- 

 sarily identical in form and function with the one which has 

 been lost. The experience of the botanists, however, shows 

 that this does not hold true in the case of plants, and a few 

 sporadic observations upon animals which, however, have 

 not been taken into consideration for this problem seemed 

 to suggest that similar conditions might be found in animals. 

 I have undertaken the task of finding out whether and by 

 what means it is possible in animals to produce at will in 

 the place of a lost organ a typically different one differ- 

 ent not only in form, but also in function. It is my purpose 

 to report the results of these experiments in the following 

 pages. 



The organs which I tried to substitute for each other in 

 these experiments are the oral and aboral poles (head and 

 foot). I have succeeded in finding animals in which it is 

 possible to produce at desire a head in place of a foot at the 

 aboral end, without injuring the vitality of the animal. The 

 animal shown in Fig. 16, a Tubularian, has by artificial means 

 been so altered that it terminates in a head at both its oral 

 and aboral ends. If, for any reason, it were necessary to 

 create any number of such bioral Tubularians, this demand 

 could be satisfied. In another Hydroid, Aglaophenia pluma, 



1 Wurzburg, 1891. The pamphlet is dated 1S91, although it appeared in 1833. 



115 



