338 C. M. CHILD. 



ganglia some portions of the ganglia remained. It is possible 

 that in some cases where the nerve roots were largely intact 

 regeneration might be almost as rapid and complete as when the 

 ganglia are present, but it is certainly impossible to make an ex- 

 tensive series of operations which are uniform in this respect. 

 Morgan's experiments of this kind included however, only 

 "several" worms. 



The only conclusion possible seems to be then that the central 

 nervous system, i. e., the nerve roots near their origin from the 

 ganglia, as well as the ganglia themselves, do affect in marked 

 degree the rapidity and amount of regeneration of the anterior 

 regions and, at least as regards the sense organs, its character as 

 well. More-over, where the ganglia, or the ganglia together with 

 the nerve roots, are removed the method of operation makes no 

 essential difference in the result. As most experiments, not only 

 on the turbellaria but on other forms, indicate, it is probable 

 that the early stages of the formation of new tissue are largely 

 or wholly independent of the nervous system, 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 affect would be in direct opposition to the well estab- 

 lished fact of the functional influence of the nervous s\>iem on 

 various parts of the organism. The rate of metabolism and 

 consequently the rate of growth i. e., provided nutritive material 

 is present in such parts must be in greater or less degree de- 

 pendent upon nerve stimuli. Such an influence of the nervous 

 -\-tem upon growth must, however, be- sharply distinguished 

 from ilie determination of differentiation of parts: the effect of 

 the functional stimulus in the stricter sense is primarily quauliia- 

 tive rather than qualitative, so far as structure i- concerned. 

 The-e point-, \\ere emplia-i/ed in my earlier paper-. 



/< .c.| I M.|! \\ |. \110K \ [( .KY, 

 l'M\ KKXI IV oh ( UK \(.O, 

 Octnlicl, KJIO. 



