202 G. E. COGHILL 



These facts lead further to the conclusion that the impulses 

 from the proprioceptive field follow the same conduction paths 

 as do those which originate in the skin. This means that action 

 in the muscular system of one side tends to excite contraction 

 in the muscles of the opposite side. This relation, indeed, may 

 be the paramount factor in adaptation that determined the 

 integration of the nervous system into physiologically distinct 

 longitudinal paths on the same side and crossed paths only in the 

 cephalic portion between the afferent path of one side and the 

 efferent path of the other, for through such a mechanism one act of 

 the swimming movement would stimulate the next with the 

 result of serial contractions which effect locomotion. The question 

 as to whether proprioceptive or exteroceptive stimulation was 

 the primary concern of the giant ganglion cells resolves itself, 

 of course, into pure conjecture; but in ontogenesis these two func- 

 tions are obviously merged into a common action through one 

 and the same mechanism. 



III. DISCUSSION OF RESULTS ' 



The literature upon the subject of the giant ganglion cells is 

 very extensive and no effort will be made here to review it in 

 detail. Comparatively recent critiques upon the literature have 

 been offered by Dahlgren ('97), Van Gehuchten ('97), Har- 

 rison ('01) and others, and since the contributions on the sub- 

 ject are almost exclusively morphological with little or no refer- 

 ence to the related physiological problems, and since the investi- 

 gations have been made upon the widely divergent forms with 

 more or less disagreement among the morphologists, it is only 

 in the way of corroboration of my own anatomical findings that 

 any help has been drawn from the literature upon my specific 

 problem of correlation of function and structure in the par- 

 ticular animals in hand. My investigations were not undertaken 

 with the idea of discovering new things in anatomy; they were 

 undertaken with a view to correlating specific structure, in par- 

 ticular animals, with known physiological characteristics of those 

 animals. My physiological experiments therefore, and not the 

 observation of others, have been my guide and my check. 



