REFLEX AND CONDITIONED ACTION 



45 



into a single neuron, whose axon divides, sending one 

 branch {tr. v. a.) to a higher visceral correlation 

 center and another branch {tr. b, /.) to the opposite 



Fig. 1. — Diagrammatic cross-section through the medulla oblongata 

 of larval Amblystoma to illustrate types of reflex connections with con- 

 vergence of different sensory systems into final common paths. On the 

 right side, fibers of gustatory sensibility {Vise. sens. X) and fibers of 

 general cutaneous sensibility {Gen. cut. X) discharge upon a single sensory 

 neuron whose axon divides to enter correlation tracts of the same and the 

 opposite side. On the left side, fibers from lateral line organs (/. /. X)y 

 from the internal ear {n. VIII), and from the skin {Gen. cut. X) dis- 

 charge upon a single neuron whose axon crosses to the opposite side and 

 then ascends to higher correlation centers through the lemniscus {Im.). 

 From Herrick and Coghill (191 5). 



side and then to a higher exteroceptive correlation 

 center. 



Evidently in these cases the reaction following 

 peripheral stimulation will be a sort of physiological 

 resultant of the interplay of the various sensory 

 excitations as they discharge into final common 



