Studies on Regulation. 465 



and the extensive literature of the interesting, although at present 

 somewhat confused question of the relation between the nervous 

 system and the formation and development of the voluntary 

 muscles (Herbst, '01, Neumann, '01, '03, Goldstein,^ '04) all 

 afford evidence that there is a relation of some sort between the 

 nervous system and the formation of certain structures, at least 

 in some stages of development. 



Regarding the nature of this relation various opinions exist. 

 The question as to the " trophic " influence of the nervous system is 

 exceedingly obscure; the formative stimuli of Herbst and others 

 are apparently regarded as entirely distinct from nervous func- 

 tional stimuli. But that some relation exists between functional 

 stimuli and the development and continued existence of certain 

 structures cannot be doubted. 



The occurrence of regeneration in plants. Protozoa and other 

 forms and in stages in which there is no visible diff^erentiation of 

 the nervous system is of course no argument against the influence 

 of the nervous system where it is present. For the development 

 of the nervous system does not add anything to the protoplasm 

 which is fundamentally diff^erent from what already exists there. 

 The nervous system is simply a more or less highly diff^erentiated 

 structure which accomplishes the transference and transforma- 

 tion of stimuli, but in its absence some method of transference, 

 however diff^use, must exist m the protoplasm. 



The following study of regeneration and other regulative phe- 

 nomena in relation to the nervous system endeavors to present 

 certain phases of the problem which seem to me important for the 

 form considered. 



The figures are diagrammatic but are drawn from careful meas- 

 urements in nearly all cases. In a number of cases the extent of 

 the intestinal branches is indicated in the figure in a simple 

 manner, no attempt being made to show the actual course of 

 branches in particular individuals. The ganglia are drawn, 

 where present, but the nerve cords are not indicated. The size 

 of the pharynx is shown as exactly as possible: in most cases the 



^ Further references to the literature of this subject may be found in Goldstein's 

 paper. 



