REGENERATION IN HYDRA ATTENUATA 



593 



delayed only when pretreatment is for 24 hours at 0.5 mg/ml (mean TDT= 

 46.20 ± 8.40) or when the concentration is increased to 1.0 mg/ml (mean TDT= 

 54.2 + 16.8). The différence for basai plate régénération is not significant. (BDT= 



Table 11. 



The Effect of RNase on Basai Plate and Tentacle Régénération. N=Number of 

 Animais. Ni = Number of Inhibited Animais. Nx = Number of Regenerated Animais. 

 %i= percent Inhibition. In any given row proximal and distal halves are derived from the 

 same animais. 







Tentacle Régénération 

 in Proximal Halves 



Basai Plate Régénération 

 in Distal Halves 



Treatment: 



N 



N; 





Vi 



/ol 



N 



N; 

 ^ i 



J> r 



/ol 



5 me/ml 



















(1) 24 Hours prior to 



Q 



y 







9 



0% 



9 







9 



0% 



(2) 5 Hours prior to 

 Transection Only . . 



16 







16 



o% 



16 







16 



f\ O / 



o% 



(3) 10 Hours prior to 

 Opération until Death 

 after Transection . . 



19 



19 







100% 



18 



18 







100% 



(4) 1 Hour prior to 



i)nprQtir\n nritil T^pq t n 

 V7pCId.llUll UI1L11 J-JCcllil 



after Transection . . 



5 



5 







100% 



5 



5 







100% 



(5) From Opération until 

 Death after Transec- 

 tion 



81 



52 



29 



64% 



81 



79 



2 



97.5% 



1 .0 mg/ml 



















(6) 5 Hours prior to 

 Transection Only . . 



5 







5 



0% 



5 







5 



0% 



(7) From Opération until 

 Death after Transec- 

 tion 



10 



8 



2 



80% 



10 



10 







100% 



1.5 mg/ml 



















(8) From Opération until 

 Death after Transec- 

 tion 



8 



8 







100% 



8 



8 







100% 



49.90 ± 7.10) (c) transected animais under continuous treatment die at times 

 comparable to intact animais under the same conditions, (d) Where inhibition is 

 less than 100% ,significantly more proximal halves regenerate than do distal 

 halves. (row 5, P < 0.01, ^=28.4) (e) At 1.0 mg/ml, two proximal halves régénéra- 



