155] 



RATE OF REGENERATION— ZELENY 



155 



tional injury. The data show essential equality between the rates of 

 regeneration under the two conditions of the experiment. This agrees 

 with the data in Experiments I and II which show no increase or decrease 

 in rate of regeneration when unlike material is removed simultaneously 

 with the removal of the organ whose rate is being studied. 



Experiment VI Amblystoma punctatum Series 4010-4025 



Three individual comparisons were made at fourteen days of the 

 right fore-leg, when it alone is removed, when the other fore-leg is also 

 removed and when the other fore-leg plus one half of the tail is removed. 

 The data are given in Table 103. In two of the three cases the individuals 



TABLE 103 



Amblystoma punctatum Series 4010-4025 



Length of regenerated fore-leg in millimeters for different degrees of injury 



Fourteen days 



Catalog 

 number 



4011, 12, 13 

 4015, 16, 17 

 4019, 20, 21 

 4023, — , 24 



Average 



Degree of injury 



One 

 fore-leg 



2.00* 

 2.00* 

 1.95 

 2.00 



1.99* 



Both 

 fore-legs 



1.77 

 1.60 

 1.82 



1.73 



Both 



fore-legs 



-f- one-half 



tail 



1.65 

 1.80 

 2.22* 

 2.00 



1.92 



with no additional regeneration are ahead of the others. The greater 

 injury gives the greater rate in one of the three. The average regener- 

 ated lengths beginning with the lowest degree of injury are respectively 

 1.99, 1.73 and 1.92 mm. The few cases may be a sufficient explanation 

 of the lack of agreement with the more extended series of Experiment I. 



Discussion 



The experiments as a whole show that a part regenerates slightly 

 more rapidly when additional material of the same kind is removed than 

 when the part alone is removed. Simultaneous removal of tail material 

 does not accelerate the regeneration of a leg nor does simultaneous re- 

 moval of a leg accelerate the regeneration of the tail. The rate in these 

 cases however is not decreased by the additional injury. The state- 



