ON VACCINATION 123 



with the very marked process of differentiation which 

 manifests itself in the diseased areas in regard to the 

 involvement of the nervine and non-nervine structures 

 respectively ; thus, as the process of exudation or excretion 

 of the specific serum and nerve plasma advances, the areolae 

 of hyperaemic cutis surrounding the areas of vesiculation 

 widen and retire before the forming or growing vesicles 

 until the stage of maturity of these is reached, when the 

 fully formed vesicular units stand out clearly defined and 

 quite anaemic amid a now scarcely visible but increasing 

 halo of hyperaemia, which halo in turn widens, culminates, 

 and finally subsides, leaving the involved nervine textures 

 and contained inspissated specific serum and connective 

 tissue to be detached and shed. This differentiation is 

 effected through or by the eruptive material raising the 

 cuticle from the underlying cutis and overflowing a more 

 or less definite area of that tissue, where it ultimately 

 "sets" or dries, and is thrown off. 



The term eruption here, we think, is a very expressive 

 one, as very exactly describing the final pathological 

 phenomena occurring in the extravasation and exudation 

 of exanthematous materies morbi generally, or at least 

 when the peculiar habitat and incubating media are found 

 within the nervous system. From the nerve terminals, 

 distributed to the areas of eruption, the vesicular contents 

 are thrown out by the sweat ducts of the nerve terminals 

 through cracks or ruptures, and, in the case of artificial 

 vaccinia, through unhealed traumatic channels in the 

 neurilemmar walls, where they push aside or submerge 

 the adjacent structural elements, leaving plateaux, cones, 

 or elevations of erupted or "volcanic" material, so to 

 speak, as monuments of subtextural or intra-neural pres- 

 sure and morbid activity the "vents" or passages by 

 which or through which these acts of eruption are effected 

 being the peri-neural lymph inter-spaces of the peripheral 

 terminal nerve tissues. Secondary toxis of the blood and 

 haemal lymph is thus averted, save in the almost constantly 

 fatal complications of haemorrhagic variola, where the 

 interposed limiting structures being broken down, and 

 the circulation of the materies morbi being no longer 

 confined within the neural lymph channels, overflows into 



