GENERAL SUMMARY. 



377 



of the Organic functions ; others with locomotion ; and others with the pro- 

 tection or withdrawal of the body from injury. Muscular movements may 

 also be excited by a stimulus directly applied to the Spinal Cord itself ( 

 363373). 



ii. The .Medulla Oblongata, or cranial prolongation of the Spinal Cord. 

 The actions of this do not essentially differ from those of the true Spinal 

 Cord ; but they are connected with different organs. This part consists 

 chiefly of the centres of the nerves of Respiration and Deglutition, two 

 functions, of which the continual maintenance is essential to the life of the 

 being; and it would seem as if these were placed within the cranium, to be 

 more secured from accidental injury. The movements concerned in Respira- 

 tion and Deglutition are, like those excited through the true Spinal Cord, of a 

 strictly reflex character, being in all instances due to an impression or stimulus 

 originating in the periphery of the system, which, being conveyed to the cen- 

 tre, excites there a motor impulse ; and they, also, are independent of Sensa- 

 tion ( 374387). 



in. The Ganglia of the nerves of Sensation, common and special, which 

 form, as it were, the continuation of the Medulla Oblongata. These appear 

 to minister to actions, which, like the Reflex, are almost necessarily excited 

 by certain stimuli, and are only in a degree controllable by the Will : but 

 which differ from those of which the Spinal Cord is the centre, in being only 

 excitable through Sensation. Reasons have been given for the belief, that 

 these ganglia are the centres of those actions, which are commonly termed 

 instinctive in the lower animals, and consensual and emotional in ourselves ; 

 these all correspond, in being performed without any idea of a purpose, and 

 without any direction of the Will, being frequently in opposition to it ( 

 422460). 



iv. The Cerebral Hemispheres or Ganglia, which are evidently the instru- 

 ments or organs of the intellectual faculties. It is probably by them alone, 

 that Ideas or notions of surrounding objects are acquired, and that these ideas 

 are made the groundwork of mental operations. They would seem, also, to 

 be the exclusive seat of Memory. The results of these operations are mani- 

 fested on the bodily frame, through the Will ; which is capable of acting, in 

 greater or less degree, on all the muscles forming part of the system of Ani- 

 mal life ( 471495). 



v. The Cerebellum, which appears to be concerned in the regulation and 

 harmonization of Muscular movements, especially those of a voluntary cha- 

 racter ( 457470). 



497. The arrangement and connections of these parts may be thus con- 

 cisely expressed : 



Tabular view of the Nervous Centres. 



Cerebral Ganglia, 



the centres of the operations 



of Intelligence and Will. 



Nerves of Special sen-") 

 sation. Motor fibres ! 

 mingled with general j 

 motor system (?). J 



Sensory Ganglia, 



the centres of Consensual, 



Instinctive, and Emotional actions. 



f Nerves of Special sen- 

 J sation. Motor fibres 

 mingled with general 

 motor system (?) . 



Cerebellic Ganglia, 

 for harmonization of general 

 muscular actions. 



32* 



