FUxNCTION OF VIBRISSAE IN BEHAVIOR OF WHITE RAT 73 



It has been said that these quaHties are in the fringe, margin 

 of consciousness yet influence the reaction just as the different 

 backgrounds unconsciously influence the visual perceptual ex- 

 perience. This is of course a statement of fact and not an 

 explanation. 



There have been eflorts to account for the state by postulat- 

 ing slight increments of sensation too feeble for consciousness 

 but which summate, so to speak, in discriminated elements. 

 These weak elements are, as Miss Washburn says, physiologically 

 sensory but not introspectively so. Miss Washburn herself would 

 try to refer the phenomena to fusion of certain sensations in 

 cortical cells and trace it back to phylogenetically old attitudes." 



Others believe with Wundt that the sense feeling or feeling 

 tone, which accompanies all sensation yet is distinct from it and 

 which also has a qualitative range, is responsible for this state 

 which is suffused by a friendly, familiar feeling. 



Recent work of Head gives evidence in man of a lower con- 

 scious center than the cortex — of a thalamic consciousness. Ac- 

 cording to Head this consciousness is non-discriminative and 

 the sensory elements are visceral, thermal and certain forms of 

 contact sensations all of which produce strongly aft'ective reac- 

 tions. He says, " Under normal circumstances the thalamic 

 element in contact sensibility rarely if ever reaches conscious- 

 ness, which is dominated by discriminative sensations of touch 

 and it only becomes a conscious factor when the influence of 

 the cortex is removed. Thus we believe that the essential organ 

 of the optic thalamus is the center for consciousness for certain 

 elements of sensation. It responds to. all stimuli capable of 

 evoking either pleasure or discomfort, or consciousness of a 

 change in state." " 



The controlling nervous mechanism from being chiefly seg- 

 mental has been steadily pushed higher and delegated to central 

 organs in the leading segments as all work in comparative neu- 

 rology shows. From animals whose segmental autonomy is prac- 

 tically complete, the development can be traced step by step 

 till man is reached whose activities are so pre-eminently domi- 

 nated by cortical influence. Yet animals like these, which have 



33 Washburn, M. R.: The Physiological Basis of the Relational Processes, Psychol. 

 Bull., 1909, vol. 6, p. 369. 



3^ Head, H.: Sensory Disturbances from Cerebral Lesions, Brain, 1911, vol. 34. 

 Pts. II and III, p. 181. 



