124 Papers from the Department of Marine Biology. 



In studying regeneration in Cassiopea I found that the rhopalia 

 exert a decided influence on the rate of regeneration, which is most 

 marked hi the early stages of any experiments, and that this influence 

 was hi the major part independent of muscular activity. The observa- 

 tions were, therefore, extended to involve other factors as the basis of 

 comparison, since it seemed evident that the influence on regeneration 

 must be in some manner exerted through fundamental metabolic 

 activity, which might be expected to be measurable on some other basis 

 than the rate of regeneration. These expectations were fulfilled when 

 either the general metabolism, as measured by total C0 2 production, 

 the loss of weight during starvation, or the changes in the rate of nerve- 

 conduction hi response to changes in temperature, was used as the 

 standard of comparison. 



The same types of operations were used in experiments on regenera- 

 tion, general metabolism, loss of weight during starvation, and the 

 influence of the sense-organs on the change in rate of nerve-conduction 

 in response to changes hi temperature, so that the results obtained by 

 use of these distinct standards of measurement are directly comparable. 



The experiments on the influence of the nerve-centers on the loss 

 of weight during starvation, on account of the operations employed, 

 necessarily involved regeneration at the same time, and in some 

 instances this factor was measured as well as that for which the 

 experiments were primarily carried out. Conversely the experiments 

 on regeneration, since only the disks were used, were carried out on 

 starving medusae and the decrease in both area and weight of the half 

 disks was often recorded for these experiments. While both these 

 factors (i. e. regeneration and decrease in size and weight) were involved 

 in the experiments on the rate of nerve-conduction, each experiment 

 extended over so short a period of time that no measurements of the 

 amount of regeneration were possible, and the loss of weight, while 

 actually small, was entirely in accord with the results obtained from 

 the more extended experiments. Thus the high rates of pulsation 

 brought about by nerve-conduction, independent of the rhopalia, 

 tended especially to emphasize the inadequacy of differences in motor 

 activity as the explanation of difference in rate of metabolism as 

 expressed by loss of weight. 



