358 FUNCTIONS OF THE NERVOUS SYSTEM. 



completely isolated from his animal powers. We should be in great danger, 

 however, of coming to an erroneous conclusion as to the real character of the 

 Cerebrum and of its operations, if we confined ourselves to the study of the 

 Human organism ; and the history of Physiological science shows, that every 

 advance of knowledge respecting its functions, has tended to limit them, whilst 

 at the same time rendering them more precise. Thus the Brain (this term, in 

 the older Anatomy, being chiefly appropriated to the Cerebrum) was accounted, 

 not merely the centre of all motion and sensation, but also the source of all 

 vitality ; the different processes of nutrition, secretion, &c., being maintained, 

 it was supposed, by a constant supply of " animal spirits," propagated from 

 the brain, along the nerves, to each individual part. The more modern doc- 

 trine, that the Sympathetic System has for its special function to supply the 

 nervous influence requisite for the maintenance of the functions of Organic 

 life, was the first step in the process of limitation ; still the Brain was regarded 

 as the centre of all the Animal functions ; and no other part was admitted to 

 possess any power independently of it. By experiments and pathological 

 observations, however, the powers of the Spinal Cord as an independent 

 centre of action were next established; and it was thus shown, that there is 

 a large class of motions, in which the Brain has no concern, and that the re- 

 moval of the Cerebral hemispheres is not incompatible (even among the higher 

 Vertebrata) with the prolonged maintenance of a sort of inert and scarcely 

 conscious life. Still, it has been usually maintained, and with great show of 

 reason, that the Cerebrum is the instrument of all psychical operations ; and 

 of all the movements which could not be assigned to the reflex action of the 

 Spinal Cord. An attempt has been made, however, in the preceding pages, 

 to show that this view is not altogether correct ; and that there is a class of 

 actions, neither reflex nor voluntary, but directly consequent upon Sensations 

 and upon the instinctive and emotional propensities associated with these, 

 which may be justly assigned to certain ganglionic centres, not less inde- 

 pendent of the Cerebrum than is the Spinal Cord itself. It has been advanced, 

 that the Cerebrum must be considered in the light of an organ siiperadded 

 for a particular purpose or set of purposes, and not as one which is essential 

 to life ; that it has no representative among the Invertebrata (except in a few 

 of the highest forms, which evidently present a transition towards the Verte- 

 brated series) ; and that, at its first introduction, in the class of Fishes, it evi- 

 dently performs a subordinate part in the general actions of the Nervous 

 System. Hence, whatever be the function, or set of functions, we assign to 

 the Cerebrum, we must keep in view the special character of the organ ; and 

 must never lose sight of the fact, that its predominance in Man does not de- 

 prive other parts of their independent powers, although it may keep the exer- 

 cise of those powers in check, and may considerably modify their manifesta- 

 tions. 



472. Before proceeding to inquire into the Physiology of the Cerebrum, 

 we may advantageously take notice of some of the leading features of its struc- 

 ture. In the first place, it forms an exception to the general plan, on which 

 the elements of ganglionic centres are arranged ; in having its vesicular sub- 

 stance on the exterior, instead of in the central part of the mass. The pur- 

 pose of this is probably to allow the vesicular matter to be disposed in such 

 a manner, as to present a very large surface, instead of being aggregated to- 

 gether in a more compact manner ; and by this means, to admit the more 

 ready access, on the one side, of the blood-vessels which are so essential to 

 the functional operations of this tissue, as well as the more ready communi- 

 cation, on the other, with the vast number of fibres, by which its influence is 

 to be propagated. There is no reason whatever to believe, that the functions 



