AN EXPERIMENTAL STUDY OF THE RELATION OF THE 

 NERVOUS SYSTEM TO THE DEVELOPING MUSCULA- 

 TURE IN THE EMBRYO OF THE FROG. 



BY 



ROSS GRANVILLE HARRISON, Ph. D., M. D., 



Associate Professor of Anatomy, The Johns Hopkins University, Baltimore 

 With IS Text Ficvres. 



While the role of the nervous s^'stem in development has been studied 

 Math increasing interest in recent years, the data are as yet of such a 

 varied and conflicting nature as to preclude the possibility of satisfactory 

 generalizations. The following pages are therefore offered as a contri- 

 bution to one phase of this subject, in the hope that through the study 

 of comparatively simple particular problems we may advance towards 

 some general conclusion.^ 



The influence of the nervous system on the regeneration of lost parts 

 has formed the subject of several experimental studies. Herbst, 99, and 

 01, has shown that in the decapod Crustacea, the optic ganglion is an 

 essential factor in determining the character of the appendage regen- 

 erated after the amputation of the eye. Morgan, 01, has reported experi- 

 ments, showing that it is the presence of the nerve cord at the cut end 

 of a decapitated earthworm that determines the regeneration of a new 

 head. In planarians, according to Bardeen, 02 and 03, the stimulus to 

 the regeneration of a new head arises from the cut surface of the central 

 nervous system. Barfurth, 02, and Rubin, 03, have investigated the 

 effect of injury to the nervous system upon the regeneration of the tail 

 and limbs in the amphibia, concluding that the destruction of the spinal 

 cord and brain has no deterrent effect upon the development of a new 

 appendage. In the case of the limbs, according to the same investigators, 

 regeneration begins normally even when the nerves, running to the stump 



^ A brief account of this work was given in a paper read before the Associ- 

 ation of American Anatomists at Washington, D. C, December 30, 1902. Hae- 

 RisoN, 03, On the Differentiation of Muscular Tissue When Removed from the 

 Influence of the Nervous System. Proc. Assoc. Amer. Anat., p. IV, Amer. 

 Journal of Anatomy, Vol. II. 



American Journal of Anatomy. — Vol. III. 



