EXTRACT XXXVII. 



ON THE RELATIVE PROPORTIONS OF THE GREY AND 

 WHITE MATTER OF THE BRAIN AND CORD, AND 

 THE MANNER OF UNION BETWEEN THE SENSORY 

 AND MOTOR AND THE PSYCHIC NEURONS. 



THE true proportions, relatively to each other, of the 

 white and grey matter, as they are distributed through- 

 out the three great central nerve organisms, the brain, 

 cord, and ganglia, is a question of the greatest interest 

 to the neurologist, but necessarily a question that must 

 remain unanswered, inasmuch as the proportion must 

 necessarily differ, in each human organism, at every 

 particular phase of its life ; it must, therefore, be regarded 

 as varying, as much as any other morphological feature, 

 or element, varies, in the various members, or units, of the 

 human race. It seems quite true, however, that the value 

 placed by science on a relatively high proportion of grey 

 matter to white is founded on truth, deducible from 

 anatomical and histological data. Thus, we may take it 

 that anatomy teaches that the grey matter is dependent 

 for the possession of its distinguishing characteristic of 

 colour on a vital, and material, difference in structure 

 between it and the white, and that the particular, or 

 peculiar, pigmentation of the grey matter would itself 

 suggest, that the active blood circulation must be the 

 determining agency, on account of the presence in its 

 blood-conveyed materials of pigmentary matter just suit- 

 able for conferring the particular shade of colouring 

 possessed by the grey matter : this suggestion, moreover, 

 would seem to be warranted also from the process of 



