374 INNERVATION. [CHAP. XI. 



We conclude tins chapter with the following inferences, which, 

 we think, the present state of knowledge justifies : 



1. The spinal cord contains within itself all the physical condi- 

 tions necessary for the mental and physical actions of the trunk 

 and extremities, so long as its connexion with the encephalon is 

 perfect through the anterior pyramids. 



2. There is no sufficient evidence to prove the existence of a 

 class of sensori-volitional fibres distinct from those which are the 

 instruments of physical actions. 



3. Each segment of the cerehro-spinal centre, whether in the 

 cranium or in the spinal canal, gives origin to its own proper 

 nerves, and has no connexion with the neighbouring segments, 

 otherwise than by commissural fibres or vesicular matter. 



4. The antero-lateral columns of the cord, with the anterior and 

 posterior horns of the gray matter, are the effective centres of mo- 

 tion and sensation of the trunk and extremities. The posterior 

 columns are longitudinal commissures, by which the influence of the 

 cerebellum is brought to bear on the various segments of the cord. 



5. When the pyramids are in a state of integrity, the corpus 

 striatum, certain accumulations of gray matter connected with the 

 nerves of the medulla oblongata, the locus niger, and the anterior 

 horns of the spinal gray matter are the centres of voluntary motion 

 to the whole body; while the optic thalami, olivary columns, and 

 posterior horns of gray matter are the centres of sensation. 



6. The medulla oblongata, when connected to the corpora striata 

 by the pyramidal fibres, is a centre of voluntary actions to those 

 parts whose nerves are derived from it ; and, in addition, it is the 

 principal centre of the actions of respiration and deglutition. 



7. The corpora quadrigemina are primary centres of visual 

 impressions, and, with a large portion of the gray matter in the 

 mesocephale, are centres of emotional actions. 



8. The cerebellum is the co-ordinator of voluntary and locomo- 

 tive actions. 



9. The convolutions of the brain are the centres of intellectual 

 actions, and are intimately associated with the mental phenomena 

 of attention, association, and memory. 



On the subjects discussed in this chapter, we refer to the more recent 

 tises on Physiology by Miiller, Wagner, and Carpenter ; to Dr. Marshall Hall's 

 writings on the Nervous System ; the most important of which will be found 

 in an octavo volume " On the Diseases and Derangements of the Nervous Sys- 

 tem," 1841; and in a quarto volume "On the Nervous System," 1843; to 

 Henle's General Anatomy; Whytt on Vital Motions; Prochaska, Annot. 

 Academicae ; Le Gallois, CEuvres ; Flourens sur le Systeme Nerveux ; 



