EXTRACT XXXIII. 



ON THE ORIGIN OF COLOUR OR PIGMENTATION IN 

 THE VARIOUS TEXTURES. 



THE occurrence of pigmentation or the deposition of 

 colouring matter in the various textures of the body 

 during the process of pathological changes in the course 

 of disease seems to be dependent on the "chapter of 

 accidents," and to be regulated by no law. Such, we are 

 led to believe, is not the case, and> indeed, it would be 

 contrary to all experience were we to look upon the 

 phenomena displayed in the colour relicts of disease as 

 representing nothing but the chaos of the battlefield, so to 

 speak, in which the agents of disease have been struggling 

 with those of health for the "mastery of the situation," 

 and in which the alterations of colour may be recognised 

 as so much wreckage. 



Before referring to the subject in its pathological aspect, 

 our explanatory efforts will be devoted to its physiological 

 bearings, in order to make more clear the foundations on 

 which we propose that the pathological superstructure and 

 its clinical outcome of deduction and guidance should be 

 built. 



Physiologically, we think we are warranted in stating 

 that all methods and varieties of animal colouration in 

 living animal nature are due to the initiative and selective 

 agency of the nervous system, by virtue of its manifold 

 "tastes," and through the various fashions and modes of 

 its working or operating throughout the whole of the 

 animal kingdom, and, also, that nature operates by a pro- 



