56 



ILLINOIS BIOLOGICAL MOXOGRAPHS 



[56 



Experiment' VII Rana clamitans Series 3557-3624 

 This experiment deals with the relative completeness of regenera- 

 tion after successive removals within single individuals. Age and ex- 

 ternal factors are not eliminated. A more complete description of the 

 experiment is given under "Completeness of Regeneration." The tail 

 length averaged approximately 17.0 mm. About one-half of the tail 

 was removed at the first operation. At succeeding operations the cut 

 came as near as possible to the border line between old and new tissue. 

 The first removals came on October 23, 1911, the second on November 

 28, the third January 3, the fourth February 9, the fifth March 16 and 

 the sixth April 4. At the time of the last removal the hind legs were 

 just starting to grow. 



The data are given in Table 36. Tlie first regeneration interval is 

 36 days, the second 36, the third 37, the fourth 36 and the fifth 39 

 days. Each one of these is more than sufficient for the completion of 

 the regenerative process. The individuals are divided into three sets, 

 A, B, and C. A, with seven individuals, has no record for the first regen- 

 eration ; the second regeneration is 9.8 mm., the third 9.3, the fourth 

 8.5 and the fifth 8.6. B, also with seven individuals, has no record for 

 the first regeneration ; the second is 9.1 mm., the third 8.9, the fourth 

 7.2 and the fifth 7.8. C, with nineteen individuals, has a first regen- 

 eration average of 8.6 mm., a second of 8.0, a third of 7.5, a fourth of 

 5.5 and a fiftli of 6.4. In all the cases there is a decrease in the amount 

 regenerated with successive removal except for the fifth regeneration, 

 which has in each case an increase over the fourth. It is probable that 



TABLE 36 



Rana clamitans Series 3564-3624 Age factor not eliminated 



Completed successive regenerations compared 



