EXTRACT XXVI. 



SCLEROSIS OF THE NERVOUS SYSTEM, OR SCLEROMA. 



IN dealing with the subject of neuroma we assigned as its 

 cause local over-accumulation or production of the intra- 

 neural or white substance of Schwann. 



In relation to the pathological disposition of the white 

 substance of Schwann within the neurilemmar coverings of 

 the nerve trunks, it may be observed that sclerosis appears 

 to us to be due to a condition the opposite of that of 

 neuroma, i.e. the white substance of Schwann is conspicu- 

 ous by its more or less complete absence, according to the 

 stage attained by the particular case of the disease in which 

 it is observed. 



In other words, neuroma is the pathological increase 

 and local accumulation or ballooning within the primitive 

 and neurilemmar sheaths of the white substance of Schwann, 

 and sclerosis is its decrease or disappearance the sclerosed 

 nerve tissue being reduced to the shrunken containing 

 sheaths of both the white substance of Schwann, and, it 

 may be, the axilemmae of the axis cylinders (should the 

 axis cylinders have also disappeared, which they usually 

 have done in advanced cases) and the overlying peri- and 

 endo-neurium. 



The neuro-keratinous material, of which these two 

 sheaths the primitive or medullary and axilemmar or 

 axis cylinder are composed, being comparatively inde- 

 structible, yet elastic, yields to pressure from within, and 

 expands indefinitely or to the vanishing point in the case 

 of neuroma, while in the case of sclerosis it shrinks and 

 hardens ; hence the meaning of the term sclerosis^ harden- 



