A Study of Growth II 



During five successive weeks the remainder of the tail was cut 

 five successive times. As a control set the records of a corre- 

 sponding number of weeks for Sets A^ and A^ (Table I) were 

 taken. These cannot, however, be considered strictly equivalent, 

 for the experiments were not started on the same dates. The 

 comparisons are therefore not very satisfactory. The animals 

 were fed as before. Four weeks after the last cut was made, a 

 time corresponding to that in the cases where the tails were cut 

 at the base, the percentage increments were as follows (because 

 of the great variation in the results of the different sets averages 

 in the two groups of sets were taken) : 

 In the three injured sets: 



Set II (Table XH) 42 .7 



SetP (Table XH) 24.5 



Set ^ (Table XII) 23 . 5 



Average 30.2 per cent 



In the normal control sets: 



Set Ai (Table I) 23 .3 



Set A2 (Table I) 29 .8 



Average 26.5 per cent 



On December i8 a similar experiment was started. Sets G^ and 

 G^ consisting of ten individuals each, after having been well fed 

 for five weeks, were divided into two sets of five individuals, 

 respectively, viz: Sets G^^ and G^^ (Table XIII), and G^^ and G^^ 

 (Table XIII). In set G^'' the tails were cut nine successive times; 

 five weeks after the last cut the percentage increment was 48 . 7. 

 In Set G^^ the tails were cut six successive times; four weeks 

 after the last cut the percentage increment was 52.3. In Set 

 G'"" the weight was so far below the average that the results are 

 of no value, and G^ became infected. For Set G* there was no 

 set which could be taken as a comparative control; but comparing 

 the thirteen weeks with a corresponding period of any normal 

 intact set the percentage increment was considerably higher. In 

 fact, the percentage in these two cases, except those obtained after 

 a period of starvation, were the highest percentages obtained in 

 any of the experiments. 



