THE SPINAL CORD. 



By C. S. SHERRINGTON. 



CONTENTS : Eeflex Action, p. 783 The Way In, p. 787 Recurrent Sensitivity, 

 p. 788 The Way Out, p. 793 Relation of Afferent to Efferent Root Cell, 

 p. 797 Reflex tonus, p. 799 Regeneration of Afferent Roots, p. 804 

 Functional Anatomy of Mediate Spinal Cell-Systems, p. 804 The Spinal 

 Grey Matter, p. 810 Reflex Capacity of Fragments of the Cord, p. 811 

 THE SPINAL ANIMAL, p. 817 Rules of Spread in " Short " Reflexes, p. 820 

 In Long Reflexes, p. 823 Influence of the Quality of the Stimulus, 

 p. 825 Summation of Stimuli, p. 828 Intensity of the Stimulus, p. 828 

 Character of the Muscular Response, p. 830 Influence of the Locus of the 

 Stimulus, p. 832 "Local Sign" and Spinal Reflexes, p. 832 Fatality of 

 Spinal Reflexes, p. 834 Influence of Condition of the Central Organ itself ; 

 Vascular Condition, p. 835 Drugs, p. 837 Influence of Associated Parts of 

 the Central Organ ; Inhibition and " Bahnung," p. 837 Co-ordinate Character 

 of the Movements, p. 843 Phasic Variation in Reflex Activity, p. 844 

 Autotomy, p. 845 Spinal " Shock," p. 845 Difference between Skeletal and 

 Visceral Musculature in regard to Shock, p. 847 Spinal Visceral Reflexes, 

 p. 849 Urinary Bladder, p. 849 Defalcation, p. 850 Sexual Spinal Reflexes, 

 p. 851 Other Visceral Reflexes, p. 853 -Reflexes affecting the Vascular Mus- 

 culature, p. 854 Significance of Spinal Reflexes, p. 856 SPINO-CEREBRAL AND 

 CEREBRO-SPINAL REACTIONS, p. 860 Conduction in the Cord, p. 861 Spinal 

 Traumatic Hypersesthesia, p. 867 TONIC FUNCTIONS OF THE CORD, p. 868 

 Automatism, p. 869 "Knee-Jerk" and Allied Phenomena, p. 870 TROPHIC- 

 FUNCTIONS OF THE CORD, p. 875 REGENERATION OF THE SPINAL CORD, p. 878. 



KEFLEX ACTION. 



SPONTANEOUSLY arising conversions of internal into external energy, such 

 as characterise the life of certain cells, for instance those of cardiac 

 muscle, are not apparent in the life of spinal cells. All purely spinal 

 reactions seem reactions to environmental change. They are reflex in 

 the sense that the environment is causally related to them, and that 

 to the environment they return again. The initiation of some is less 

 directly and demonstrably traceable from the environment than that 

 of others. The former are by a convenient usage often termed " spon- 

 taneous." The latter or obviously reflex comprise for the most part 

 the relatively simpler. The distinctions drawn between reflex and 

 spontaneous reactions naturally alter from time to time. The tendency 

 with increasing knowledge of physical and chemical agents has been 

 for an increasing number of reactions to be included as reflex. 



Among the properties of living matter (bioplasm), those which by 

 their high development in the nervous system may be said to charac- 

 terise the physiological qualities of that system, are excitability to 

 certain kinds of stimuli, spatial transmission of the excited state, and 

 ability to control the liberation of energy in tissues adjoint to them- 





