122 PHYSIC 



provided the introduction of foreign disease-producing 

 viri be avoided, and the specific virus, or viri, allowed a 

 free and untrammelled opportunity of effecting the benign 

 mission on which it is sent ; this, therefore, necessitates 

 the guarded use of bactericidal agents in case, perchance, 

 they act too literally on the principle embraced in the old 

 saying, "set a thief to catch a thief." In short, purity, 

 simplicity, and the avoidance of unnecessary detail in the 

 performance of an operation which was first successfully 

 performed by nature would seem to dictate the manner 

 of its performance. 



A few more thoughts on the subject of vaccination 

 have suggested themselves since the above study was 

 closed, and, lest they should be forgotten, they had better 

 be recorded here. The vaccine vesicles or "spots," as 

 they are popularly called, as well as the vesicles of small- 

 pox, are, we contend, nervine in origin and almost entirely 

 nervine in the extent of tissue involved, and affect, 

 secondarily only, the other tissues of the skin, as can be 

 plainly seen on examination and analysis of the process 

 of vesiculation. Thus the mature vesicles, when they 

 may be said to have "reached their height," are semi- 

 transparent, non-vascular, raised areas of cutaneous tissue 

 loculated and why? because they are determined by the 

 disposition and arrangement of the terminal nervature 

 and filled with an unstained serum, containing the specific 

 virus of the disease, which may be drawn off free from 

 blood or left to undergo a process of inspissation and, 

 finally, shedding, without, except in haemorrhagic cases of 

 smallpox, invading the blood circulatory structures or 

 vasculature, the surrounding hyperremic vesicular areolae 

 subsiding with the declension of the specific pathological 

 neural changes, when the scabs or crusts are shed as the 

 collective nervine necrosed elements of the affected areas, 

 hence the scars left are found to be devoid of the ordinary 

 peripheral nerve terminal extensions, these having been 

 destroyed, and the skin consequently left to that extent 

 anaesthetic. 



In closely observing the sequence of the pathological 

 events displayed in the evolution, maturation, and sub- 

 sidence of the rash of vaccinia or variola, we are struck 



