464 



tion of the spinal marrow, and of the excito-motory system of nerves, 

 and of an exclusive series of physiological and pathological pheno- 

 mena : — If in a turtle, from which the head and sternum have been 

 removed, we lay bare the sixth or seventh intercostal nerve, and sti- 

 mulate it either by means of the forceps or galvanism, both the ante- 

 rior and posterior fins, with the tail, are immediately moved with 

 energy. Hence the author infers the existence : 1st, of a true spinal 

 marrow, physiologically distinct from the chord of intra-spinal nerves j 

 2ndly, of a system of excito-motory nerves, physiologically distinct 

 from the sentient and voluntary nerves : and, 3rdly, of currents of 

 nervous influence, incident, upwards, downwards, and reflex with re- 

 gard to the spinal marrow. 



A review is then taken of the labours of preceding physiologists 

 relative to the functions of the nervous system : in which the author 

 criticises the reasonings of Whytt, Legallois, Mr. Mayo, Dr. Alison, 

 and Professor Muller ; and illustrates his own peculiar views by several 

 experiments and pathological observations, which appear to him to 

 show that muscular movements may occur, under circumstances imply- 

 ing the cessation of sensation, volition, and every other function of the 

 brain ; and that these phenomena are explicable only on the hypothesis 

 that impressions made on a certain set of nerves, which he terms excito- 

 motory, are conveyed to a particular portion of the spinal marrow 

 belonging to that system, and are thence reflected, by means of cer- 

 tain motor nerves, upon certain sets of muscles, inducing certain ac- 

 tions. The same actions may also be the result of impressions made 

 directly either on the spinal marrow or on the motor nerves. He 

 accordingly considers that the whole nervous system may be divided 

 into, — 1st, the cerebral, or the sentient and voluntary; 2ndly, the 

 true spinal, or the excitor and motor ■ and, 3rdly, the ganglionic, or 

 the nutrient, the secretory, &c. The excito-motory system presides 

 over ingestion and exclusion, retention and egestion, and over the 

 orifices and sphincters of the animal frame: it is therefore the ner- 

 vous system of respiration, deglutition, &c, and the source of tone 

 in the whole muscular system. The true spinal system is the seat or 

 nervous agent of the appetites and passions, but is also susceptible 

 of modification by volition. This theory he proceeds to apply to the 

 explanation of several phenomena relating to the motions of the eye- 

 lids, pharynx, cardia, larynx, muscles of inspiration, sphincter ani, 

 expulsors of the faeces and' semen, to the tone of the muscular system 

 generally, and to actions resulting from the passions. Lastly, he 

 considers its application to various diseased states of the same func- 

 tions, as manifested in cynic spasm, vomiting, asthma, tenesmus, 

 strangury, crowing inspiration, convulsions, epilepsy, tetanus, hydro- 

 phobia, and paralysis. 



Reference is made, in the course of the paper, to several drawings 

 and diagrams, which, however, have not yet been supplied. 



