1892.] On the Nerve-roots of the Lumbosacral Plexus. 



67 



Thus our standard exceeds the cells of the Board of Trade by 

 rather over one of our units, or about O'OOOS volt. 



If we take the E.M.F. of our standard as 1*4342 volts at 15% the 

 cells of the Board of Trade average in E.M.F. about 1-4339 volts at 

 15° C, or 1-4321 volts at 62° Fahr. 



III. "Note on the Functional and Structural Arrangement of 

 Efferent Fibres in the Nerve-roots of the Lumbo-sacral 

 Plexus." (Preliminary Communication.) By C. S. SHER- 

 RINGTON, M.A., M.B., &c. Communicated by Professor M. 

 Foster, Sec. K.S. Received March 14, 1892. 



At the commencement of some observations on the reflex mechan- 

 isms of the spinal cord in Macacus rhesus, difficulties were en- 

 countered which made it desirable to attempt for that animal a some- 

 what particular examination of the distribution of the efferent and 

 afferent spinal nerve-roots belonging to the lumbo-sacral plexus. 

 The present communication has reference to the distribution of the 

 efferent fibres of the roots. 



Reil,* Scarpa, f A. Monro, J and Soemmering§ all paid considerable 

 attention to the arrangement of the root-bundles in the limb plexuses, 

 but physiological work upon the subject commenced with Van Deen,|| 

 J. Miiller,^" and Panizza.** The former two gave an anatomical 

 significance to the plexus, the last a physiological. At Miiller's 

 suggestion, renewed research was undertaken by H. Kronenbergft 

 in 1835. Kronenberg confirmed Miiller's observations as to the in- 

 dividual inconstancy of the contribution made by any spinal root to 

 the nerve cords of the plexus ; he also concluded that the excitation 

 of a single nerve-root before its entrance into the plexus produces 

 contraction of almost all the muscles of the limb ; and that the 

 arrangement is intended to protect against fatigue. Later, 

 Eckhardt,^J working in Ludwig's laboratory, arrived at somewhat 

 similar conclusions. He stated that a great number of muscles 

 obtain nerve-fibres each of them from several nerve-roots ; that there 

 is a good deal of individual variation ; that when a nerve-root is 



* 'De Nervorum Structura,' p. 14. 

 f ' De Grangliis et Plexibus.' 



X ' Observations on the Structure and Functions of the Nervous System,' p. 34. 

 § ' Anatom.,' Pars Yta. 



|| 'De Differentia et Nexu inter Nervos Vita? Anim. et Organ.,' Leyden, 1834. 

 «[ ' Physiol, des Menschen,' vol. 2, p. 586. 

 ** ' Annali Universali di Medicina.' 



tf Essay ('De Struct, et Yirtut. Plexuum Nervorum'), Berlin, 1836. 

 XX 'Zeits. f. Eat. Med., ; vol. 1, p. 306, 1849. 



j 2 



