THE HISTORICAL DEVELOPMENT OF NEUROPHYSIOLOGY 



37 



f). OO If! 



Tiglira Murculi [eamdum auto- "''■'"'■ ^-^ 



FIG. 23. Lc//.- Descartes' sketch of reciprocal muscles of the eye (/Jf Humine, the Latin translation by 

 Schuyl). Center: a redrawing showing closure of valves on relaxation, opening on contraction to allow 

 animal spirits to How in and swell the muscle QL' Homme, the French edition of 1677). Right: Sherring- 

 ton's diagram of the connections and actions of two cells of a dorsal root ganglion. The plus sign 

 indicates that at the central synapses the afferent impulses excite the ipsilateral flexor muscle and 

 the contralateral extensor, while inhibiting the ipsilateral extensor and the contralateral flexor 

 muscle. (From Sherrington, C. S. The Integratwe Ac/inn nf Ike Nervous Svslem, 2nd ed. Cambridge: 

 Cambridge, 1947.) 



(205) in Montpellier. The latter favored a peripherally 

 exerted nervous influence acting against an inherent 

 elasticity of muscle. 



In 1868 Hering (206) and Breuer(207) found in the 

 respiratory system a parallel to Bell's experiment 

 whereby distention of the lung acting through the 

 pulmonary branch of the vagus inhibited inspiration 

 while exciting expiration, the well-known Hering- 

 Breuer reflex. And in 1883 Kronecker (208) working 

 on the swallowing reflex in Ludwig's laboratory with 

 his American pupil, Meltzer, demonstrated the in- 

 hibitory action of the superior laryngeal nerve on in- 

 spiratory muscles during contraction of expiratory 

 ones. The reflex nature of .swallowing had been recog- 



205. Duces, Antoine. Traile de Physiologie Comparee de I'homme 

 et des Animaux. Montpellier & Paris, 1838; Compt. rend. Sac. 

 de biol. March 17, 1847. 



206. Hering, Karl Ewald Konstantin (i 834-1918). Die 

 Selbststeuerung der Athmung durch den Nervus Vagus. 

 Silzber. Akad. Wiss. Wien 57; 672, 1868. 



207. Breuer, Joseph (1842-1925). Die Selbstseuerung der 

 Athmung durch den Nervus Vagus. Sitzber. Akad. Wiss, 

 Wien 58: 909, 1868. 



208. Kronecker, Karl Hugo (1839-1914) and Samuel 

 James Meltzer (1851-1920). Der Schluckmechanismus, 

 seine Erregung und seine Hemmung. Arch. Anat. Physiol. 

 Suppl. : 328, 1883. 



nized by Marshall Hall (195) in 1823 and the direct 

 afferent nerve for it had been identified by Magcndie 

 (209) to be the glossopharyngeal, but the reciprocal 

 effect had not been noted by them. 



It is the fact that there are no inhibitory nerves to 

 vertebrate skeletal muscle that drew the whole subject 

 of reflex inhibition into the central nervous system. 

 With the realization that reflex inhibition had its site 

 in the central nervous system, attention was turned to 

 the connection between the incoming sensory element 

 of the arc and the motor component, to the junction 

 between them, in other words, to the synapse (Sher- 

 rington's word). That there might be an interaction of 

 a synaptic kind between neurons in the periphery had 

 occurred to several workers, one among whom was 

 Sigmund Freud (210). His work on fresh-water crabs 

 and his illustrative sketches of how he conceived of 

 intercommunication between the axons of their 

 ganglia came close to what is now termed an ephapse, 

 although he pictured transverse crossings that sug- 

 gest a uniting of fibers rather than a contiguity. 



209. Magendie, F. Lei^ons sitr les fonctions du systhne nerveux. 

 Paris, 1839. 



210. Freud, Sigmund (1856- 1939). Uber den Bau der Nerven- 

 fasern und Nervenzellen beim Flusskrebs. Sitzber. Akad. 

 Wiss. Wien 85: 9, 1882. 



