THE AXIAL GRADIENTS IN HYDROZOA. 



391 



The effect on the relative times of regeneration of apical and 

 basal pieces by cutting them above and below a lateral branch 

 is of course slight but nevertheless it is evident in most cases. 

 If the experiments given in Table VIII. are compared with those 



TABLE VIII. 



RECORDS OF MASS EXPERIMENTS WITH APICAL AND BASAL PIECES OF EQUAL 

 LENGTH, THE APICAL PIECES BEING TAKEN IN FRONT OF THE FIRST BRANCH 

 THE BASAL PIECES BELOW THE BRANCH. 

 Columns under a and b give number of hydranths emerged at time indicated. 



Controls in Table III. and IV., exp. 10 for exp. 12; exps. 26 and 27 for exp. 28, 30 



and 34; exp. 35 for exp. 36. 



in Tables III. and IV., it will be found that in general more basal 

 pieces have regenerated in the experimental series when the 

 same number of apical pieces have regenerated in both control 

 and experimental series. This appears chiefly in the early part 

 of the regeneration period. A few such comparisons may be 

 pointed out; in making them it is necessary to select experiments 

 in which the total number of regenerating pieces is similar in 

 experiment and control, since the number of regenerated apical 

 pieces in the early stages of an experiment is greater relative to 

 the basal pieces, the greater the total number of pieces. In 

 experiment I2&, Table VIII., 2, 9, and 19 basal pieces have 



