384 LIBBIE H. HYMAX. 



The rate of regeneration of pieces of the stem of Tubularia is, 

 as has long been known, dependent in large part upon the tem- 

 perature and the temperature coefficient of this process is 

 described as corresponding to that of chemical reasions (Moore, 

 '10). The rate of regeneration is not, however, wholly dependent 

 upon the temperature at which regeneration occurs but is to 

 some degree affected by the temperature at which the particular 

 stems used had been living previous to their utilization. Thus 

 in the experiments recorded in Tables III. and IV., it can be 

 noted that summer material regenerates more slowly at 13 C. 

 than does winter material at 12 C. While other possible 

 explanations of this fact could be suggested it seems reasonable 

 in the light of other results along this line to suppose that this 

 is another case of acclimation to temperature; material living for 

 some time at low temperature has elevated the rate of its chemical 

 processes above that which would result if the material were 

 suddenly lowered to the same temperature from a higher tem- 

 perature a procedure usually practised in experiments on the 

 temperature coefficient. 



F. RATE OF REGENERATION OF DISTAL AND PROXIMAL PIECES 



OF UNEQUAL LENGTH. 



Banus refers to Child's experiments on pieces of unequal 

 length in which Child found that longer pieces will regenerate 

 slightly faster than shorter ones provided the factor of level is 

 eliminated by always making the apical pieces the shorter pieces. 

 Since apical pieces regenerate faster than basal pieces no con- 

 clusions could be drawn regarding the effect of length on the time 

 of regeneration unless the apical piece were the shorter. Banus 

 has "repeated" this experiment and claims that the longer piece 

 always regenerates first regardless of level. Here Banus has 

 again misrepresented Child's statements and he has not in 

 reality repeated Child's experiment. Child distinctly states that 

 changes in the length of the piece "produce only very slight or 

 no appreciable differences in time of emergence of oral hydranths 

 provided the length of the piece is above a certain minimum. 

 But with reduction in length below the minimum the appearance 

 of the hydranth is delayed and this retardation increases with 



