A Study of Grotvth 25 



III RESULTS OF THE SERIES OF I906-O7 (PART l) INTERPRETED 

 IN THE LIGHT OF FACTS OBTAINED IN THE PRESENT SERIES 

 OF EXPERIMENTS 



The facts obtained in the present series of experiments in many 

 cases show or indicate the causes of many of the irregularities 

 of the Series of 1906-07. 



In Sets A^ and A^ (Table I), composed of three males and three 

 females respectively, where the food and temperature conditions 

 were the same, the percentage increment in A^ was 23.3 and in 

 A^ was 29.8. The initial weight, however, of the first was 2.006 

 grams, while of the second it was 1.661 gram. The difference 

 in initial weight would seem to account for the difference in the 

 rate of growth. 



In Sets C^ and O (Table III) there was a similar difference, not 

 so great, but which may be interpreted in the same way. 



Initial Increment 

 weight per cent 



Set Ci 1.853 18.4 



Set C2 2. 1 1 14.5 



In Set D^ (Table IV) where the animals were injured by cutting 

 off the tail at the base, and in Sets A^ and A^ the normal control, 

 the initial weights and the percentage increments were as follows: 



Injured animals Normal animals 



After In. wt. Increment 



In. wt. operation Increment grams per cent 



grams grams per cent Set A' 2.066 H-'? 



Set Di 2-253 1.986 19.5 Set .^2 i.66i 20.3 



Ajter nine weeks 



After nine weeks Set A' 2 .066 23 .3 



Set D' 2.253 i.^^d 30.4 Set A2 1.661 29.8 



The percentage in the injured set was greater than in one control 

 and less than in the other, but when the initial weight is considered 

 the difference between the two control sets may be explained. 

 Based on this comparison, the evidence in favor of a greater 

 percentage in the injured set is more striking. 



