RATE OF REGENERATION IN CASSIOPEA 27 



Walter '11 for Triton. The second of these special cases has been 

 shown by the studies of Morgan, Child, and Goldfarb to be con- 

 ditioned by influences other than the presence of the nerve 

 centers. The work of Steele has shown also that the removal 

 of an eye stalk is not followed by the regeneration of a hetero- 

 morphic structure in several species of Crustacea. 



While none of these workers has laid any stress on the fact that 

 the nervous system, exerts an influence on the rapidity of the 

 early stages of regeneration it has been noted in several instances 

 that the initial stages of regeneration are more rapid in the con- 

 trol animals than in those from which the nervous system has 

 been removed. Thus Goldfarb (op. cit.), page 664, states that 

 in salamanders the hind limb develops more slowly on the side 

 from which the dorsal ganglia innervating the leg had been re- 

 moved than does that of the opposite side in which the ganglia 

 remained when the spinal cord had already been removed. In 

 a table on pages 665 and 666 he shows that this result was ob- 

 served in all the specimens recorded save two, in one of which 

 the regeneration was, at the time of measurement, equal for 

 both legs, while in a single specimen the regeneration was most 

 rapid from the side from which the ganglia were removed. 



In tadpoles from which the caudal portion of the spinal cord 

 had been removed regeneration of the tail took place more slowly 

 than in the control animals in which the cord was uninjured (p. 

 672). Again concerning Earthworms from which the head had 

 been cut off" and several millimeters of the ventral cord removed 

 he says (p. 708): ''The head regenerates rather later in these 

 operated animals than in control animals.'* In the regeneration 

 of the arms of the starfish (p. 711) a similar observation is 

 recorded. 



Goldfarb is, however, of the opinion that "Any severe in- 

 jury. . . , whether involving the nerves or any other tissue, 

 retards regeneration." Stockard, on the other hand, concluded 

 that in Cassiopea, as Morgan had already shown for a consid- 

 erable number of animals, the rate of regeneration increased in 

 proportion to the extent of injury and that the deeper the cut — 



