118 ILLISOIS BIOLOGICAL MONOGRAPHS [118 



Experiment II Raxa clamitans First regenerations op the tail, 

 Series 3676-3765 



The tadpoles were collected on December 9, 1911, and the tail remov- 

 als were made on January 8. Measurements were taken 4, 6, 8, 10, 12%, 

 18 and 56 days after the opei'ations. The operations were at six levels 

 approximating 6, 10, 17, 30, 48 and 62 per cent of the original tail 

 length. For the first of these levels only two individuals with an average 

 removal of 1.5 mm. are available, for the second five individuals with 

 2.6 mm., for the third three with 4.6 mm., for the fourth eight with 8.2 

 mm., for the fifth five with 13.0 mm. and for the sixth five with 16.7 mm. 

 The rates of regeneration per day are given in table 60 and the graphs 

 for the rates in Figure 56. 



Tlie specific rates are given in Table 61. Averaging these values 

 so as to include all the different levels for each period the specific rates 

 are 0.018 for to 4 days, 0.046 for 4 to 6 days, 0.057 for 6 to 8 days, 

 0.037 for 8 to 10 days, 0.026 for 10 to I21/2 days, 0.002 for 121/0 to 18 

 days and — 0.001 for 18 to 56 days. The graph is shown in the unbroken 

 line in Figure 53. Using only the four deepest levels the average specific 

 rates are respectively 0.013," 0.042, 0.045, 0.036, 0.025, 0.006 and 0.000 

 giving essentially the same form of curve as for the average of all levels. 



The accelerations of rate are shown in Table 62 and the accelerations 

 of specific rate in Table 63 and in the unbroken line of Figure 54. The 

 average accelerations of rate per day are respectively -|-0.07S, 0.000, 

 — 0.022, —0.042, —0.025 and 0.000 mm. The average accelerations of 

 specific rate including all levels are respectively +0.011, — 0.001, 

 —0.007, —0.0075, —0.003 and 0.000 and including only the four deepest 

 levels, +0.009, 0.000, —0.004, —0.005, —0.003 and 0.000. As for sec- 

 ond regenerations the only plus acceleration is between 2 and 5 days 

 and the most rapid deci-ease takes place between 9 and 11^/4 days. 



The percentage increments per day are shown in Table 64 and in the 

 unbroken line of Figure 55. The values are respectively 98, 29, 17, 6, 

 1 and percent per day giving approximately the same form of curve 

 as for second regenerations. 



In general the first regenerations agree with the second but on the 

 whole the second regenerations reach their maximum earlier and are 

 more rapid than the first up to the time of maximum rate. The first 

 are more rapid than the second after the maximum. 



