INFLUENCE OF NERVE ON REGENERATION. 47 



tion between the nerve and the regeneration of the leg is that of 

 Wolff. 1 He found that if the nerve-cord were destroyed in the 

 region of origin of the leg nerve that the leg regenerated at the 

 normal rate. Since the spinal ganglion was left after this opera- 

 tion, its presence may have sufficed to produce the result. In 

 fact, nerves were found in the new foot. In order to remove the 

 ganglion also, a piece of the spinal column was cut out including 

 cord and ganglion. Six individuals that survived this operation 

 showed that after the first proliferation of new material had taken 

 place growth came to a standstill for a time and then began 

 again. The result suggests, Wolff thinks, that the standstill was 

 due to the lack of nerve connection, while the renewal of growth 

 was due to the reestablishing of a new nerve connection. In 

 fact the disabled leg showed some signs of having regained its 

 power of motion. 



Wolff discusses the question whether the period of standstill 

 may not have been due to the lack of function or activity of 

 the leg while its later growth was due to its regaining its loco- 

 motor function. He argues that this is probably not the case, 

 but that the nerve connection is directly responsible for the 

 result. 



A student of Busfurth's, R. Rubin, 2 has obtained similar 

 results. What part the nervous connection plays in these cases 

 is still obscure. Morgan and Davis 3 have found that for the 

 regeneration of the tail of the tadpole, the presence of the noto- 

 chord and not the nervous system is the important factor. 



COLUMBIA UNIVERSITY. 



1 Virchow 1 s Arthiv, CLXIX., 1902. 



2 Archiv Enfw. Mec/i., XVI., 1903. 

 * Archiv Ent-w. Mech., XV., 1903. 



