714 THE POPULAR SCIENCE MONTHLY. 



strumentality of the sensorium — that is, of that aggregate of sense-ganglia, 

 through the instrumentality of which we become conscious of external sense- 

 impressions, and thus feel sensations? " (p. 109). 



"In this point of view the sensorium is the one centre of consciousness for 

 visual impressions on the eye (and by analogy on the other organs of sense), and 

 for ideational or emotional modifications on the cerebrum — that is, in one case 

 for sensations, when we become conscious of sense impressions ; and, in the 

 other, for ideas and emotions, when our consciousness has been afiected by cere- 

 bral changes. According to this view, we no more think or feel with our cere- 

 brum than we see with our eyes; but the ego becomes conscious through the 

 same instrumentality of the retinal changes, which are translated (as it were) 

 by the sensorium into visual sensations, and of the cerebral changes, which it 

 translates into ideas and emotions " (p. 111). 



It would be impossible to put in clearer language this new doc- 

 trine, the psychical and the physiological counterparts of which are 

 thus made to fit so accurately and consistently. The first question, 

 however, which ought to have been entertained is the basement of 

 l^hysiological fact upon which all this imposing edifice has been erect- 

 ed. We are not aware of any, over and above the experiments of 

 Flourens, who showed that birds performed consensual movements, 

 apparently indicating the retention of consciousness, after the cere- 

 brum had been removed down to the optic thalami and the corpora 

 striata. But in complement to these interesting experiments, we have 

 the fact that frogs perform consensual movements which may be taken 

 to indicate the retention of consciousness after the sj^inal cord itself 

 has been divided. The movements of Flourens's pigeons no more 

 prove the retention of consciousness than those of a decapitated frog, 

 which " when acetic acid be applied over the upper and inner part of 

 the thigh, the foot of the same side will wipe it away ; but if that 

 foot be cut ofi", after some ineffectual efforts, and a short period of in- 

 action, the same movement will be made by the foot of the opposite 

 side" (p. 68). 



If, under the light of these facts, it be difficult to maintain that the 

 seat of consciousness is not diffused through the central parts of the 

 cerebrum aiid of the spinal cord, the pathological fact that in the hu- 

 man being the optic thalamus or the corpus striatum may be funda- 

 mentally changed in consistence and structure by disease, without loss 

 of consciousness, is a barrier against the acceptance of Dr. Carpenter's 

 theory, which, as yet, we are unable to make our way over, under, or 

 through ; and, at present, our conclusion is, that unconscious cerebra- 

 tion is an hypothesis all in the air, and unsupported by any foundation 

 of physiological fact. 



Whether the activities of the cerebral convolutions are unattended 

 with consciousness until they have been reflected upon the sensorium, 

 is a question which perhaps physiological experiment, or even more 

 likely pathological research, will answer before long. In the mean 

 while we are exceedingly incredulous, and retain our faith in the old 



