ON VACCINATION 121 



vaccinia the neuro-keratine walls of the recently trau- 

 matised or abraded nerve terminals, we may assume, give 

 way or rupture at the seat of trauma under the disruptive 

 influence of the vis a tergo set up by, or due to, the retro- 

 gression of the tainted lymph or vaccine, and discharge 

 it, with the effect that the neurilemmar sheaths of these 

 terminals are disorganised or necrosed, so as to permit its 

 intermixture with and possible destruction of more or less 

 of the surrounding non-nervous texture, and afterwards 

 of the formation of escharotic tissue from which the 

 cerebro-spinal nerve elements are absent or sparsely 

 present, and where only the trophic nerve elements are 

 left to preside over the processes of nutrition and renewed 

 development. 



In this connection it might further be assumed that 

 destruction, traumatism, and necrosis of the sensory ter- 

 minal nerve arborisations are not followed by their renewal 

 or re-growth in the substituted cicatricial tissues. The 

 truth of this assumption is verifiable by testing the sensory 

 condition of the vaccinal cicatrices and the "pits" result- 

 ing from smallpox. The depressed surfaces and ' ' pits " 

 seem, in fact, to be respectively due largely to the non- 

 presence in them of the cerebro-spinal nerve elements 

 consequent on their destruction during the continuance 

 of the vaccinal and variolar lesions and to their imperfect, 

 or non-renewal. 



The manner of the performance of the operation of 

 vaccination must be regarded as a matter of importance, 

 and is a subject on which much diversity of opinion pre- 

 vails. Since Jenner's introduction of it, it has been 

 performed by all manner of persons, lay as well as pro- 

 fessional, and at the present day we have living and 

 smallpox-proof individuals amongst us who owe their 

 immunity and protection to the services of one or all of 

 these. In its performance, therefore, we may take it that 

 its manner does not embody any great or insuperable 

 difficulty. The introduction of the appropriate virus or 

 lymph, destitute of any admixture with other viri, into 

 the system of the unprotected is the desideratum, and 

 this can be effected perfectly safely in mostly all of many 

 manners affected by the initiated and other vaccinators, 



