374 GENERAL VIEW OF THE HUMAN FUNCTIONS. 



are distributed to the sensory surfaces and to the muscular apparatus of the 

 body generally; but at the summit of the Cord we find a peculiar set of gan- 

 glionic centres, included in that part which is distinguished as the Medulla 



Oblongata, whose nerves are distributed to the organs of Respiration, Deglu- 

 tition, &c., and whose function consists in sustaining the muscular move- 

 ments whose performance is essential to the continuance of these functions. 

 The movements in question are purely reflex; and there is no other reason for 

 distinguishing the endowments of the Medulla Oblongata from those of the 

 Spinal Cord, save that which arises out of the specialty of the purposes to which 

 the movements are subservient. At the summit of the Spinal Cord, and partly 

 lodged in the substance of the Medulla Oblongata, we find the series of Sensory 



Ganglia, which may in their totality be considered as making up the Sensorium. 

 This includes the centres to which proceed the nerves of " special sense ;" and 

 we may probably rank with it a pair of ganglionic masses (the " thalami optici,") 

 towards which certain afferent fibres of the spinal trunks appear traceable, that 

 do not find their ganglionic centre in the spinal ganglia, but seem to pass up- 

 wards to the sensorium, that they may there excite sensational changes of the 

 " common" or tactile kind. From these Sensory Ganglia, we do not find any 

 motor trunks ostensibly originating; but fibres pass downwards from them into 

 the Spinal cord, which either directly enter its efferent nerve-trunks, or which 

 serve to excite to action the ganglia from which those trunks arise; so that 

 " reflex" actions are performed by the instrumentality of the sensorial ganglia, 

 which, however, differ from those of the spinal cord, in requiring Sensation as a 

 necessary link in the series of changes. The Sensory ganglia are, therefore, the 

 centres of the consensual or sensori-motor actions. The whole of this series of 

 ganglionic centres constitutes the purely automatic portion of the Nervous sys- 

 tem, whose operations, when not interfered with by the Cerebrum, are, like 

 those of Insects (whose entire nervous system corresponds with the automatic 

 portion of that of Man), entirely instinctive. And their independent action 

 seems to be the source, not merely of all those movements which are originally 

 instinctive, but of many others which come by habit to be performed involun- 

 tarily when the attention is otherwise engaged; these have been termed " se- 

 condarily automatic." 



393. But in Man, as in all other animals possessed of Intelligence, by which 

 the Will is animated and directed, we find a superadded organ, the Cerebrum, 

 which is not itself the centre of either sensory or motor nerves, but which derives 

 from the automatic apparatus just described all its stimulus to action, and 

 employs it as its instrument of operation on the muscular system. The functions 

 of this organ, which are purely mental, are first excited by the sensations called 

 forth in the Sensory ganglia, which, being conveyed to the cerebrum, give rise 

 through its instrumentality to Ideas ; and these may become the subject of 

 Reasoning processes, which react on the body by an exertion of the Will. Al- 

 though it has been customary to regard the Will as directly operating on the 

 muscular system, yet we shall hereafter find reason to consider it as exerting its 

 power through the medium of the Automatic apparatus, to which its determina- 

 tions are transmitted, and by which they are carried into execution. But ideas 

 with which the feelings of pleasure or pain are associated, constitute Emotions ; 

 and these, if strongly excited, may act downwards upon the muscles through the 

 medium of the automatic apparatus, quite independently of the will, and even 

 in opposition to it. And there are certain peculiar states of the mind, in which 

 the power of the Will is completely suspended, and in which Ideas alone seem 

 capable of exciting movements. Thus the Cerebral ganglia are the instruments 

 of two kinds of action that may be considered essentially "reflex," as being ex- 

 ecuted in respondence to external impressions, without any volitional or purposive 

 direction; these impressions either acting simply through ideas, and thus pro- 



