PROCESS OF REGENERATION 



147 



ready pointed out, that it is not a truly independent part. The 

 reversal of the gradient after section appears most clearly in a 

 form hke Dero, where the posterior region is of small extent. 

 Table 4 is the record of such an experiment on Dero limosa; 

 ten worms were cut up into sixth pieces, and put immediately 

 into 5^^ KCN. The experiment was begun at 12.45, and the 

 number of pieces completely disintegrated recorded at fifteen 

 minute intervals. 



In general, then, the regions which in the intact animal have 

 lowest susceptibility have highest suceptibility after section, 

 while the regions having high susceptibility in the whole are not 

 much altered by section, with the exception of the posterior end 



TABLE 4 



which although already having a high rate is somewhat simu- 

 lated by section. In the case of Lumbriculus and the tubificids, 

 where over half of the body is involved in the posterior rise of 

 metabolic rate, the susceptibility of all pieces except the most 

 anterior is increased by section, that of the middle pieces relatively 

 most but not enough to raise it above that of posterior pieces 

 which had a much higher rate before section. The gradient is 

 therefore not reversed in these forms; it simply is raised to a 

 higher level, and becomes less steep. 



The st'mulation following section may be explained as due to 

 the severance of conduction and correlation paths. The fact 

 that the head and anterior regions in general are little stimulated 

 by isolation indicates that they are relat vely independent of 



