1 5 o PHYSIC 



ing, according to the literature of the subject, from that 

 of a plum-stone to an oval tumour, in some cases little 

 less than a foot in longitudinal diameter (one was eleven 

 by ten inches). 



The contents of the tumour, which are comparatively 

 homogeneous, may thus be regarded as the inspissated 

 and quasi-organised white substance of Schwann collected 

 into masses, due to the failure, on a large scale, of the 

 nodes of Ranvier of the affected nerve fibres, and the 

 yielding of the primitive or containing sheaths of that 

 substance, together with that of the overlying layers of 

 the endo- and peri-neurium. 



The initiating and determining cause of the tumour may 

 be a more or less temporary or persistent local stasis of 

 the circulation of the white substance of Schwann within 

 its containing sheath or sheaths, which becomes permanent, 

 and ends in more or less local or general tumefaction at 

 one or several different points throughout the whole or 

 part of the involved nerve trunk or trunks. 



The size of the tumour or neuromatous enlargement, we 

 may take it, is determined by its shorter or longer con- 

 tinuance and its greater or lesser solidarity from the more 

 or less complete exosmosis of the more fluid parts of its 

 contained materials. 



The unvarying character of the contents of the so-called 

 growths or tumours may also be regarded as almost a proof 

 that their formation has taken place within, and the 

 materials of which they are composed have been drawn 

 entirely from, the proper nerve structures or elements, and 

 characteristically moulded by the peri-neurium, this view 

 holding good in the solitary and multiple varieties of the 

 disease alike. 



The consistence of the contents of these tumours, it 

 ought to be added, varies between that of a thin jelly 

 and ordinary gristle ; hence an analogy to the formation 

 of gristle in joints and osseous development histologically. 



The disease may be regarded in most cases, more 

 especially of the multiple variety, as due to a constitutional 

 predisposition or susceptibility, and the contemporary 

 incidence and influence of exciting causes the predis- 

 position or susceptibility being or consisting of a too 



