Ii6 Phenomena Refuting Simple Epigenesis 



locking of the two organisms which would give a most 

 asymmetrical and irregular dividing surface. 



The continuation of development in the tail frag- 

 ment of the tadpole seems to speak likewise against both 

 epigenesis and pre formation. For in his experiments 

 upon tadpoles, Born has proven the accuracy of Vulpian's 

 statement that the amputated tails not only continue to 

 live for sometime (some even thirteen days), but con- 

 tinue to grow and to differentiate into their various 

 tissues. He has further observed the following processes 

 of new formation. 



"A few days after the amputation, the margins of 

 the fin of the amputated tail commence to grow over the 

 cut surface of the axis ; they unite in front of it to form 

 a high semicircular tail fin. The axis is not entirely 

 without participation in this process, for prolongations 

 of the notochord as well as of the spinal cord grow 

 into the newly formed fin, but the metameric muscu- 

 lature show r s nothing like this and terminates sharply at 

 the original surface of amputation. But this prolonga- 

 tion of the notochord, like that of the spinal cord, even 

 in the most favorable instances, scarcely extends half as 

 far forward in front of the cut end of the original axis 

 as does the newly formed marginal fin. This latter is 

 formed of typical embryonic mucous connective tissue 

 with a few pigment cells scattered through it. I have 

 not been able to discover in it any rudiments of vessels." 



"This observation teaches then," continues Born, 

 "that the provision of yolk in the tail end cut off from 

 a tadpole does not serve merely, as Vulpian has already 

 shown, for further growth, and further differentiation 

 of the tissues, and for the formation of a new structure 

 growing out from the cut surface, but it shows that 



