A Study of Grozuth 7 



animals were starved, it was found that after a period of eighteen 

 weeks the former had gained 44.2 per cent of the initial weight, 

 while the latter had lost 73.6 per cent of the initial weight. 



V EFFECT OF INJURY ON THE RATE OF GROWTH 



To determine the effects of injury, the tails of the salamanders 

 were cut off, either once at the base, or six or even nine successive 

 times, a very small piece each time. 



On October 23 the tails of six salamanders were cut at the 

 base, the animals being weighed before and after the operation, 

 enough time being left between the weighings so that the cut 

 surface had ceased to bleed. The animals were then weighed 

 once a week for five weeks. Control normal animals were also 

 weighed, and kept under the same conditions as the injured ones. 

 The feeding was, as in the experiments above, about 153 mg. 

 of beef a week. At the end of a period of five weeks the results 

 were as follows: The injured set D^ (Table IV) had gained 

 (average) 19.5 per cent of the original weight after the tails were 

 cut, while the percentage gained in the two normal control sets 

 A^ and A^ (Table I) was 14.3 and 20.3, respectively, the average 

 between the two control sets being 17.3 per cent. After the first 

 week the individuals of the injured set had almost made up the 

 weight lost by cutting their tails. Another set, started November 

 6, also showed this to be the c*ase; the first week after the injury 

 the percentage increase was 13.6, the entire weight of the tails 

 being almost made up. 



The experiment described above was repeated November 13, 

 the number of animals used being somewhat larger. Six sets 

 consisting often individuals each were used, the animals in three 

 of the sets being injured by cutting off the tails at the base. Each 

 set was controlled by a set of normal animals with tails intact. 

 The injured and the normal control sets in every case were fed 

 the same amount of beef, 153 mg. (average), and were kept under 

 identical conditions. At the end of five weeks the results in 

 percentage increments were as follows: 



