148 Papers from the Department of Marine Biology. 



similar course of events in earthworms, starfish, and amphibians. 

 This result, on the other hand, is opposed to the conclusion of Child 

 (1910) that ''as most experiments not only on the Turbellaria, but on 

 other forms, indicate, it is probable that the early stages of the forma- 

 tion of new tissue are largely or wholly independent of the nervous 

 system." A later part of the same statement is in perfect accord with 

 my result, as follows: ''But it is difficult to understand how the 

 nervous system of an adult animal could fail to affect the amount and 

 rapidity of growth in a regenerating part composed largely of muscles 

 and sense-organs. Absence of such an effect would be in direct 

 opposition to the well-established fact of the functional influence of the 

 nervous system on various parts of the organism." 



Morgulis (1912) concludes from his experiments on brittle-stars that 

 the presence at the cut surface of the radial nerve, either with or without 

 its being in continuity with the remainder of the nervous system, is 

 a "conditio sine qua non" for normal regeneration and that the pres- 

 ence — ^purely as a mechanical matter, not the functional activity — 

 of the nerve is the important factor in regeneration. This is in direct 

 opposition to my results. A study of the figures illustrating his paper 

 shows, nevertheless, that the arms in which the nervous connection is 

 undisturbed (control) regenerates most rapidly. 



As to the nature of this influence, it is evident from the study of the 

 rate of general metabolism of half-disks with and without sense-organs 

 that it is closely associated with if not identical with the control of the 

 general metabolism of the animal. The latter experiments have not 

 been carried far enough to give a definite answer to the question of 

 whether or not there is a gradual decline in the difference in the rate 

 of metabolism corresponding to that shown in regeneration. 



This result clearly supports the general contention of Child, that the 

 influence of the nervous system on regeneration is indirect rather than 

 direct, but does not confirm his statement that there is a direct relation- 

 ship between the rapidity of regeneration and the "characteristic 

 motor activity of the parts concerned." It is shown, on the contrary, 

 that motor activity may be greatly increased without altering to a 

 proportional extent either the rate of regeneration or general metabo- 

 lism. 



The rate of regeneration appears to be sunply one expression of the 

 general metabolic activity of an organism and consequently to be 

 subject to the control of the nerve-centers in the same manner as the 

 many other functional activities — for some of which, at least, a direct 

 nervous control can not be denied. 



