204 G. E. COGHILL 



Hani and Beard (in his earlier paper) are quoted by other author? 

 as being of the same opinion with Studnicka. More recent 

 observers, however, discredit this interpretation and fail to find 

 the endings of the fibers in the myotomes. The general interpre- 

 tation, which has been insisted upon in recent years, that the 

 dorsal part of the cord is sensory, probably created a presump- 

 tion in the minds of later observers against the idea that these 

 fibers end in the myotomes, for such endings had been interpreted 

 as motor. My anatomical preparations, however, seem to be un- 

 equivocal on this point, and my physiological results are equally 

 positive concerning the existence of a functional proprioceptive 

 field of stimulation. The harmony between my anatomical and 

 physiological observations adds weight to my conclusion that the 

 giant ganglion cells are muscle sensory as well as skin sensory 

 in function. 



That the same neurone may carry impulses from the skin and 

 the muscle as my anatomical findings indicate is also against the 

 presumption of current anatomy and physiology. In the consid- 

 eration of this point, however, it should be borne in mind that 

 the giant ganglion cell is obviously a primitive structure. This 

 seems to be conceded by all morphologists who have studied 

 the subject. In my opinion, the giant ganglion cells represent 

 the afferent element of the nervous mechanism of the earliest 

 chordates that propelled themselves in locomotion by means of a 

 mesodermal muscular system. In such an ancestral form, as in 

 the ontogenetic stage of development now under consideration, 

 physiological differentiation in the synaptic centers between 

 cutaneous and muscle sensory impulses could be of little, if any, 

 significance. The paramount feature of adaptation of the reflex 

 mechanism of these embryos is immediately centered in locomotion 

 and not in differential sensory functions. Frbm the point of 

 view of the efficiency of this mechanism as it actually works in the 

 life of amphibian embryos there is no reason apparent why im- 

 pulses should not be carried from the skin and the muscle to the 

 spinal cord through the same neurone. 



With reference to the subepithelial structures of the giant 

 ganglion cells, the repetition of Wintrebert's ('04) experiments 



