THE CEREBRUM, AND ITS FUNCTIONS. 741 



strong, but because, the intelligence being undeveloped, it acts without control 

 or direction from the will. 



5. The Cerebrum, and its Functions. 



773. We come, in the last place, to consider the functions of that portion of 

 the Nervous Centres, which is evidently, in Man, the predominant organ of his 

 whole system ; being not merely the instrument of his reasoning faculties, but 

 also possessing a direct or indirect control over nearly all the actions of his cor- 

 poreal frame, save those purely vegetative processes which are most 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 ren- 

 dering 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 pro- 

 cesses 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 doctrine, 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 func- 

 tions ; 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 removal 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 the originator 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 correct; and that there is a class 

 of actions, neither excito-motor nor voluntary, but directly consequent upon 

 Sensations, and constituting (with the excito-motor) the truly instinctive actions 

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

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

 that the Cerebrum must be considered in the light of an organ superadded 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 Vertebrated 

 series) : and that, at its first introduction, in the class of Fishes, it evidently 

 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 deprive other parts of 

 their independent powers, although it may keep the exercise of those powers in 

 check, and may considerably modify their manifestations. 



774. Before proceeding to inquire into the Physiology of the Cerebrum, we 

 may advantageously take notice of some of the leading features of its structure. 

 In the first place, it forms an exception to the general plan on which the ele- 

 ments of ganglionic centres are arranged : in having its vesicular substance on 

 the exterior, instead of in the central part of the mass. The purpose of this is 



