210 Journal of Comparative Neurology. 



tent the limitations of neurology as a handmaid of psychology. 

 The problem is, in reality, very simple so long as the bounds of 

 neurology are not overstepped. 



We naturally approach the subject from the aesthesodic 

 side. In other words, we enquire, does the mass of stimuli 

 which forms the incentive to all subjectivity reach consciousness 

 in more than one form, and, if so, are these various forms cap- 

 able of producing different "aspects" of reality? Of course 

 an affirmative reply can be given to the question in its first 

 form at once. All stimuli ol the higher senses habitually pre- 

 sent themselves to the cortical or conscious centres in a double 

 way. In the case of vision, for example, the perfect visual stim- 

 ulus reaches the tectum and undergoes the complicated analysis 

 which the structure and genetic relations of the latter to the 

 retina so strongly suggest and then effects coordinations with 

 the occulomotor mechanism, completing the entire visual act, 

 even to the connections with the automatic efferent centres. 

 No cortical consciousness is involved in these processes but 

 the latter is provided for by " associational tracts " connecting 

 with the occipital cortex where other cortical connections are 

 effected. Our point here is simply that the whole visual process 

 is completely out of the conscious sphere and mechanism and 

 that a separate loop is developed in higher animals to effect the 

 cortical communication. Now when an objective image is 

 formed on the retina and the physiological processes of vision, 

 accomodation, etc. follow, a second and entirely distinct process 

 may be induced, under suitable circumstances, in the cortex to 

 which alone the perception of the object is due. A decorti- 

 cated dog will see perfectly well and avoid obstacles, but is un- 

 able to perceive or recognize the object. 



Under other circumstances it may happen that the cortical 

 region may be excited by a stimulus other than those arising in 

 the optic lobes and there will follow a more or less perfect re- 

 vival of some of the various processes which had previously 

 been inaugurated by a visual excitement. The second form of 

 cortical excitement is due to a vestige and may be called a ves- 

 tigeal or indirect. This, is often spoken of loosly as a subjective 



